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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 04/09/25 2:04 am, Lorenzo Stoakes wrote: > On Wed, Sep 03, 2025 at 11:16:34AM +0530, Dev Jain wrote: >> Currently khugepaged does not collapse a region which does not have a >> single writable page. This is wasteful since non-writable VMAs mapped by > As discussed elsewhere in the thread, you really need to clarify that you > mean the PTE is writable. This is far too vague otherwise. Okay. > >> the application won't benefit from THP collapse. Therefore, remove this >> restriction and allow khugepaged to collapse a VMA with arbitrary >> protections. > It's weird thie history of this, it looks like we were super conservative > at first, and then introduced this 'at least one PTE writable' thing in > commit 10359213d05a ("mm: incorporate read-only pages into transparent huge > pages"), but it doesn't really explain why you even need (at least) a > writable page. > > Perhaps a pre-PAE thing... (David?) we already do the refcount stuff > though, so it's hard to understand. > > It seems the main case for anon where it'd matter is swapped in pages > read-faulting for a R/W mapping (as read-faulting R/W mappings would just > get you the zero page which vm_normal_page() would exclude anyway). > > But not sure why we'd be reticent to collapse those anyway... you'd just > cahnge R/W bit on PMD instead of PTE? > > Yeah it's bizarre. > > I can't really see why your change shouldn't be done... > > >> Along with this, currently MADV_COLLAPSE does not perform a collapse on a >> non-writable VMA, and this restriction is nowhere to be found on the >> manpage - the restriction itself sounds wrong to me since the user knows > I'm not sure why a man page would talk about PTE scanning implementation > details? Sure, the manpage shouldn't talk about that, but the consequence of this PTE scanning implementation is that a read-only VMA won't be collapsed, so the manpage should have at least talked about mapping protections. So a user doing a PROT_READ mapping and then doing madvise(MADV_COLLAPSE) will receive -EINVAL which is extremely bizarre. > > But I guess as you say you're thinking specifically of a read-only VMA that > naturally has read-only PTE's as as result... > >> the protection of the memory it has mapped, so collapsing read-only >> memory via madvise() should be a choice of the user which shouldn't >> be overriden by the kernel. > NIT: overriden -> overridden. > >> On an arm64 machine, an average of 5% improvement is seen on some mmtests >> benchmarks, particularly hackbench, with a maximum improvement of 12%. > Nice! > > Is this on a raw metal machine, or a VM? I thik it's important to clarify > details like this. > > Please state precisely what you tested this on. I am guessing these benchmarks run in a container but I'll clarify this. > >> Signed-off-by: Dev Jain > Can't find any problem with this, and doesn't really seem like it'd be > problematic so: > > Reviewed-by: Lorenzo Stoakes Thanks. > >> --- >> RFC->v1: >> Drop writable references from tracepoints >> >> RFC: >> https://lore.kernel.org/all/20250901074817.73012-1-dev.jain@arm.com/ >> >> I can see performance improvements on mmtests run on an arm64 machine >> comparing with 6.17-rc2. (I) denotes statistically significant improvement, >> (R) denotes statistically significant regression (Please ignore the >> numbers in the middle column): > Let's drop the numbers in the middle column then please, this is going into the > commit log, let's not put extranous information there. I'll go study some Unix commands to drop that middle column :) > >> +------------------------------------+----------------------------------------------------------+-----------------------+--------------------------+ >> | mmtests/hackbench | process-pipes-1 (seconds) | 0.145 | -0.06% | >> | | process-pipes-4 (seconds) | 0.4335 | -0.27% | >> | | process-pipes-7 (seconds) | 0.823 | (I) -12.13% | >> | | process-pipes-12 (seconds) | 1.3538333333333334 | (I) -5.32% | >> | | process-pipes-21 (seconds) | 1.8971666666666664 | (I) -2.87% | >> | | process-pipes-30 (seconds) | 2.5023333333333335 | (I) -3.39% | >> | | process-pipes-48 (seconds) | 3.4305 | (I) -5.65% | >> | | process-pipes-79 (seconds) | 4.245833333333334 | (I) -6.74% | >> | | process-pipes-110 (seconds) | 5.114833333333333 | (I) -6.26% | >> | | process-pipes-141 (seconds) | 6.1885 | (I) -4.99% | >> | | process-pipes-172 (seconds) | 7.231833333333334 | (I) -4.45% | >> | | process-pipes-203 (seconds) | 8.393166666666668 | (I) -3.65% | >> | | process-pipes-234 (seconds) | 9.487499999999999 | (I) -3.45% | >> | | process-pipes-256 (seconds) | 10.316166666666666 | (I) -3.47% | >> | | process-sockets-1 (seconds) | 0.289 | 2.13% | >> | | process-sockets-4 (seconds) | 0.7596666666666666 | 1.02% | >> | | process-sockets-7 (seconds) | 1.1663333333333334 | -0.26% | >> | | process-sockets-12 (seconds) | 1.8641666666666665 | -1.24% | >> | | process-sockets-21 (seconds) | 3.0773333333333333 | 0.01% | >> | | process-sockets-30 (seconds) | 4.2405 | -0.15% | >> | | process-sockets-48 (seconds) | 6.459666666666666 | 0.15% | >> | | process-sockets-79 (seconds) | 10.156833333333333 | 1.45% | >> | | process-sockets-110 (seconds) | 14.317833333333333 | -1.64% | >> | | process-sockets-141 (seconds) | 20.8735 | (I) -4.27% | >> | | process-sockets-172 (seconds) | 26.205333333333332 | 0.30% | >> | | process-sockets-203 (seconds) | 31.298000000000002 | -1.71% | >> | | process-sockets-234 (seconds) | 36.104000000000006 | -1.94% | >> | | process-sockets-256 (seconds) | 39.44016666666667 | -0.71% | >> | | thread-pipes-1 (seconds) | 0.17550000000000002 | 0.66% | >> | | thread-pipes-4 (seconds) | 0.44716666666666666 | 1.66% | >> | | thread-pipes-7 (seconds) | 0.7345 | -0.17% | >> | | thread-pipes-12 (seconds) | 1.405833333333333 | (I) -4.12% | >> | | thread-pipes-21 (seconds) | 2.0113333333333334 | (I) -2.13% | >> | | thread-pipes-30 (seconds) | 2.6648333333333336 | (I) -3.78% | >> | | thread-pipes-48 (seconds) | 3.6341666666666668 | (I) -5.77% | >> | | thread-pipes-79 (seconds) | 4.4085 | (I) -5.31% | >> | | thread-pipes-110 (seconds) | 5.374666666666666 | (I) -6.12% | >> | | thread-pipes-141 (seconds) | 6.385666666666666 | (I) -4.00% | >> | | thread-pipes-172 (seconds) | 7.403000000000001 | (I) -3.01% | >> | | thread-pipes-203 (seconds) | 8.570333333333332 | (I) -2.62% | >> | | thread-pipes-234 (seconds) | 9.719166666666666 | (I) -2.00% | >> | | thread-pipes-256 (seconds) | 10.552833333333334 | (I) -2.30% | >> | | thread-sockets-1 (seconds) | 0.3065 | (R) 2.39% | >> +------------------------------------+----------------------------------------------------------+-----------------------+--------------------------+ >> >> +------------------------------------+----------------------------------------------------------+-----------------------+--------------------------+ >> | mmtests/sysbench-mutex | sysbenchmutex-1 (usec) | 194.38333333333333 | -0.02% | >> | | sysbenchmutex-4 (usec) | 200.875 | -0.02% | >> | | sysbenchmutex-7 (usec) | 201.23000000000002 | 0.00% | >> | | sysbenchmutex-12 (usec) | 201.77666666666664 | 0.12% | >> | | sysbenchmutex-21 (usec) | 203.03 | -0.40% | >> | | sysbenchmutex-30 (usec) | 203.285 | 0.08% | >> | | sysbenchmutex-48 (usec) | 231.30000000000004 | 2.59% | >> | | sysbenchmutex-79 (usec) | 362.075 | -0.80% | >> | | sysbenchmutex-110 (usec) | 516.8233333333334 | -3.87% | >> | | sysbenchmutex-128 (usec) | 593.3533333333334 | (I) -4.46% | >> +------------------------------------+----------------------------------------------------------+-----------------------+--------------------------+ > This is nice, but is clearly hugely exceeding the column width we should have in commit messages. > > Let me use emacs's nice features to make life easy for you :) - Oh you did it for me, thank you so much! > > +-------------------------+--------------------------------+---------------+ > | mmtests/hackbench | process-pipes-1 (seconds) | -0.06% | > | | process-pipes-4 (seconds) | -0.27% | > | | process-pipes-7 (seconds) | (I) -12.13% | > | | process-pipes-12 (seconds) | (I) -5.32% | > | | process-pipes-21 (seconds) | (I) -2.87% | > | | process-pipes-30 (seconds) | (I) -3.39% | > | | process-pipes-48 (seconds) | (I) -5.65% | > | | process-pipes-79 (seconds) | (I) -6.74% | > | | process-pipes-110 (seconds) | (I) -6.26% | > | | process-pipes-141 (seconds) | (I) -4.99% | > | | process-pipes-172 (seconds) | (I) -4.45% | > | | process-pipes-203 (seconds) | (I) -3.65% | > | | process-pipes-234 (seconds) | (I) -3.45% | > | | process-pipes-256 (seconds) | (I) -3.47% | > | | process-sockets-1 (seconds) | 2.13% | > | | process-sockets-4 (seconds) | 1.02% | > | | process-sockets-7 (seconds) | -0.26% | > | | process-sockets-12 (seconds) | -1.24% | > | | process-sockets-21 (seconds) | 0.01% | > | | process-sockets-30 (seconds) | -0.15% | > | | process-sockets-48 (seconds) | 0.15% | > | | process-sockets-79 (seconds) | 1.45% | > | | process-sockets-110 (seconds) | -1.64% | > | | process-sockets-141 (seconds) | (I) -4.27% | > | | process-sockets-172 (seconds) | 0.30% | > | | process-sockets-203 (seconds) | -1.71% | > | | process-sockets-234 (seconds) | -1.94% | > | | process-sockets-256 (seconds) | -0.71% | > | | thread-pipes-1 (seconds) | 0.66% | > | | thread-pipes-4 (seconds) | 1.66% | > | | thread-pipes-7 (seconds) | -0.17% | > | | thread-pipes-12 (seconds) | (I) -4.12% | > | | thread-pipes-21 (seconds) | (I) -2.13% | > | | thread-pipes-30 (seconds) | (I) -3.78% | > | | thread-pipes-48 (seconds) | (I) -5.77% | > | | thread-pipes-79 (seconds) | (I) -5.31% | > | | thread-pipes-110 (seconds) | (I) -6.12% | > | | thread-pipes-141 (seconds) | (I) -4.00% | > | | thread-pipes-172 (seconds) | (I) -3.01% | > | | thread-pipes-203 (seconds) | (I) -2.62% | > | | thread-pipes-234 (seconds) | (I) -2.00% | > | | thread-pipes-256 (seconds) | (I) -2.30% | > | | thread-sockets-1 (seconds) | (R) 2.39% | > +-------------------------+--------------------------------+---------------+ > > +-------------------------+------------------------------------------------+ > | mmtests/sysbench-mutex | sysbenchmutex-1 (usec) | -0.02% | > | | sysbenchmutex-4 (usec) | -0.02% | > | | sysbenchmutex-7 (usec) | 0.00% | > | | sysbenchmutex-12 (usec) | 0.12% | > | | sysbenchmutex-21 (usec) | -0.40% | > | | sysbenchmutex-30 (usec) | 0.08% | > | | sysbenchmutex-48 (usec) | 2.59% | > | | sysbenchmutex-79 (usec) | -0.80% | > | | sysbenchmutex-110 (usec) | -3.87% | > | | sysbenchmutex-128 (usec) | (I) -4.46% | > +-------------------------+--------------------------------+---------------+ > > >> mm/khugepaged.c | 9 ++------- >> 1 file changed, 2 insertions(+), 7 deletions(-) >> >> diff --git a/mm/khugepaged.c b/mm/khugepaged.c >> index 4ec324a4c1fe..a0f1df2a7ae6 100644 >> --- a/mm/khugepaged.c >> +++ b/mm/khugepaged.c >> @@ -676,9 +676,7 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma, >> writable = true; >> } >> >> - if (unlikely(!writable)) { >> - result = SCAN_PAGE_RO; >> - } else if (unlikely(cc->is_khugepaged && !referenced)) { >> + if (unlikely(cc->is_khugepaged && !referenced)) { >> result = SCAN_LACK_REFERENCED_PAGE; >> } else { >> result = SCAN_SUCCEED; >> @@ -1421,9 +1419,7 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm, >> mmu_notifier_test_young(vma->vm_mm, _address))) >> referenced++; >> } >> - if (!writable) { >> - result = SCAN_PAGE_RO; >> - } else if (cc->is_khugepaged && >> + if (cc->is_khugepaged && >> (!referenced || >> (unmapped && referenced < HPAGE_PMD_NR / 2))) { >> result = SCAN_LACK_REFERENCED_PAGE; >> @@ -2830,7 +2826,6 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start, >> case SCAN_PMD_NULL: >> case SCAN_PTE_NON_PRESENT: >> case SCAN_PTE_UFFD_WP: >> - case SCAN_PAGE_RO: >> case SCAN_LACK_REFERENCED_PAGE: >> case SCAN_PAGE_NULL: >> case SCAN_PAGE_COUNT: >> -- >> 2.30.2 >> > I guess you delay the final cleanup so you can combine it with tracepoint > removal in next patch, not really sure why they're separate but meh not a > big deal. --------------auC0hCJI3d00D4noU0ENBizz Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 7bit


On 04/09/25 2:04 am, Lorenzo Stoakes wrote:
On Wed, Sep 03, 2025 at 11:16:34AM +0530, Dev Jain wrote:

Currently khugepaged does not collapse a region which does not have a
single writable page. This is wasteful since non-writable VMAs mapped by

As discussed elsewhere in the thread, you really need to clarify that you
mean the PTE is writable. This is far too vague otherwise.

Okay.




the application won't benefit from THP collapse. Therefore, remove this
restriction and allow khugepaged to collapse a VMA with arbitrary
protections.

It's weird thie history of this, it looks like we were super conservative
at first, and then introduced this 'at least one PTE writable' thing in
commit 10359213d05a ("mm: incorporate read-only pages into transparent huge
pages"), but it doesn't really explain why you even need (at least) a
writable page.

Perhaps a pre-PAE thing... (David?) we already do the refcount stuff
though, so it's hard to understand.

It seems the main case for anon where it'd matter is swapped in pages
read-faulting for a R/W mapping (as read-faulting R/W mappings would just
get you the zero page which vm_normal_page() would exclude anyway).

But not sure why we'd be reticent to collapse those anyway... you'd just
cahnge R/W bit on PMD instead of PTE?

Yeah it's bizarre.

I can't really see why your change shouldn't be done...



Along with this, currently MADV_COLLAPSE does not perform a collapse on a
non-writable VMA, and this restriction is nowhere to be found on the


      

        
manpage - the restriction itself sounds wrong to me since the user knows


      

      
I'm not sure why a man page would talk about PTE scanning implementation
details?

    

    


    

    
Sure, the manpage shouldn't talk about that, but the consequence of this
PTE scanning implementation is that a read-only VMA won't be collapsed,
so the manpage should have at least talked about mapping protections.
So a user doing a PROT_READ mapping and then doing madvise(MADV_COLLAPSE)
will receive -EINVAL which is extremely bizarre.



    

      

But I guess as you say you're thinking specifically of a read-only VMA that
naturally has read-only PTE's as as result...



      

        
the protection of the memory it has mapped, so collapsing read-only
memory via madvise() should be a choice of the user which shouldn't
be overriden by the kernel.


      

      
NIT: overriden -> overridden.



      

        
On an arm64 machine, an average of 5% improvement is seen on some mmtests
benchmarks, particularly hackbench, with a maximum improvement of 12%.


      

      
Nice!

Is this on a raw metal machine, or a VM? I thik it's important to clarify
details like this.

Please state precisely what you tested this on.

    

    

    
I am guessing these benchmarks run in a container but I'll clarify this.



    

      



      

        
Signed-off-by: Dev Jain <dev.jain@arm.com>


      

      
Can't find any problem with this, and doesn't really seem like it'd be
problematic so:

Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>

    

    

    
Thanks.



    

      



      

        
---
RFC->v1:
Drop writable references from tracepoints

RFC:
https://lore.kernel.org/all/20250901074817.73012-1-dev.jain@arm.com/

I can see performance improvements on mmtests run on an arm64 machine
comparing with 6.17-rc2. (I) denotes statistically significant improvement,
(R) denotes statistically significant regression (Please ignore the
numbers in the middle column):


      

      
Let's drop the numbers in the middle column then please, this is going into the
commit log, let's not put extranous information there.

    

    

    
I'll go study some Unix commands to drop that middle column :)



    

      



      

        
+------------------------------------+----------------------------------------------------------+-----------------------+--------------------------+
| mmtests/hackbench                  | process-pipes-1 (seconds)                                |                 0.145 |                   -0.06% |
|                                    | process-pipes-4 (seconds)                                |                0.4335 |                   -0.27% |
|                                    | process-pipes-7 (seconds)                                |                 0.823 |              (I) -12.13% |
|                                    | process-pipes-12 (seconds)                               |    1.3538333333333334 |               (I) -5.32% |
|                                    | process-pipes-21 (seconds)                               |    1.8971666666666664 |               (I) -2.87% |
|                                    | process-pipes-30 (seconds)                               |    2.5023333333333335 |               (I) -3.39% |
|                                    | process-pipes-48 (seconds)                               |                3.4305 |               (I) -5.65% |
|                                    | process-pipes-79 (seconds)                               |     4.245833333333334 |               (I) -6.74% |
|                                    | process-pipes-110 (seconds)                              |     5.114833333333333 |               (I) -6.26% |
|                                    | process-pipes-141 (seconds)                              |                6.1885 |               (I) -4.99% |
|                                    | process-pipes-172 (seconds)                              |     7.231833333333334 |               (I) -4.45% |
|                                    | process-pipes-203 (seconds)                              |     8.393166666666668 |               (I) -3.65% |
|                                    | process-pipes-234 (seconds)                              |     9.487499999999999 |               (I) -3.45% |
|                                    | process-pipes-256 (seconds)                              |    10.316166666666666 |               (I) -3.47% |
|                                    | process-sockets-1 (seconds)                              |                 0.289 |                    2.13% |
|                                    | process-sockets-4 (seconds)                              |    0.7596666666666666 |                    1.02% |
|                                    | process-sockets-7 (seconds)                              |    1.1663333333333334 |                   -0.26% |
|                                    | process-sockets-12 (seconds)                             |    1.8641666666666665 |                   -1.24% |
|                                    | process-sockets-21 (seconds)                             |    3.0773333333333333 |                    0.01% |
|                                    | process-sockets-30 (seconds)                             |                4.2405 |                   -0.15% |
|                                    | process-sockets-48 (seconds)                             |     6.459666666666666 |                    0.15% |
|                                    | process-sockets-79 (seconds)                             |    10.156833333333333 |                    1.45% |
|                                    | process-sockets-110 (seconds)                            |    14.317833333333333 |                   -1.64% |
|                                    | process-sockets-141 (seconds)                            |               20.8735 |               (I) -4.27% |
|                                    | process-sockets-172 (seconds)                            |    26.205333333333332 |                    0.30% |
|                                    | process-sockets-203 (seconds)                            |    31.298000000000002 |                   -1.71% |
|                                    | process-sockets-234 (seconds)                            |    36.104000000000006 |                   -1.94% |
|                                    | process-sockets-256 (seconds)                            |     39.44016666666667 |                   -0.71% |
|                                    | thread-pipes-1 (seconds)                                 |   0.17550000000000002 |                    0.66% |
|                                    | thread-pipes-4 (seconds)                                 |   0.44716666666666666 |                    1.66% |
|                                    | thread-pipes-7 (seconds)                                 |                0.7345 |                   -0.17% |
|                                    | thread-pipes-12 (seconds)                                |     1.405833333333333 |               (I) -4.12% |
|                                    | thread-pipes-21 (seconds)                                |    2.0113333333333334 |               (I) -2.13% |
|                                    | thread-pipes-30 (seconds)                                |    2.6648333333333336 |               (I) -3.78% |
|                                    | thread-pipes-48 (seconds)                                |    3.6341666666666668 |               (I) -5.77% |
|                                    | thread-pipes-79 (seconds)                                |                4.4085 |               (I) -5.31% |
|                                    | thread-pipes-110 (seconds)                               |     5.374666666666666 |               (I) -6.12% |
|                                    | thread-pipes-141 (seconds)                               |     6.385666666666666 |               (I) -4.00% |
|                                    | thread-pipes-172 (seconds)                               |     7.403000000000001 |               (I) -3.01% |
|                                    | thread-pipes-203 (seconds)                               |     8.570333333333332 |               (I) -2.62% |
|                                    | thread-pipes-234 (seconds)                               |     9.719166666666666 |               (I) -2.00% |
|                                    | thread-pipes-256 (seconds)                               |    10.552833333333334 |               (I) -2.30% |
|                                    | thread-sockets-1 (seconds)                               |                0.3065 |                (R) 2.39% |
+------------------------------------+----------------------------------------------------------+-----------------------+--------------------------+

+------------------------------------+----------------------------------------------------------+-----------------------+--------------------------+
| mmtests/sysbench-mutex             | sysbenchmutex-1 (usec)                                   |    194.38333333333333 |                   -0.02% |
|                                    | sysbenchmutex-4 (usec)                                   |               200.875 |                   -0.02% |
|                                    | sysbenchmutex-7 (usec)                                   |    201.23000000000002 |                    0.00% |
|                                    | sysbenchmutex-12 (usec)                                  |    201.77666666666664 |                    0.12% |
|                                    | sysbenchmutex-21 (usec)                                  |                203.03 |                   -0.40% |
|                                    | sysbenchmutex-30 (usec)                                  |               203.285 |                    0.08% |
|                                    | sysbenchmutex-48 (usec)                                  |    231.30000000000004 |                    2.59% |
|                                    | sysbenchmutex-79 (usec)                                  |               362.075 |                   -0.80% |
|                                    | sysbenchmutex-110 (usec)                                 |     516.8233333333334 |                   -3.87% |
|                                    | sysbenchmutex-128 (usec)                                 |     593.3533333333334 |               (I) -4.46% |
+------------------------------------+----------------------------------------------------------+-----------------------+--------------------------+


      

      
This is nice, but is clearly hugely exceeding the column width we should have in commit messages.

Let me use emacs's nice features to make life easy for you :) -

    

    

    
Oh you did it for me, thank you so much!



    

      

+-------------------------+--------------------------------+---------------+
| mmtests/hackbench       | process-pipes-1 (seconds)      |        -0.06% |
|                         | process-pipes-4 (seconds)      |        -0.27% |
|                         | process-pipes-7 (seconds)      |   (I) -12.13% |
|                         | process-pipes-12 (seconds)     |    (I) -5.32% |
|                         | process-pipes-21 (seconds)     |    (I) -2.87% |
|                         | process-pipes-30 (seconds)     |    (I) -3.39% |
|                         | process-pipes-48 (seconds)     |    (I) -5.65% |
|                         | process-pipes-79 (seconds)     |    (I) -6.74% |
|                         | process-pipes-110 (seconds)    |    (I) -6.26% |
|                         | process-pipes-141 (seconds)    |    (I) -4.99% |
|                         | process-pipes-172 (seconds)    |    (I) -4.45% |
|                         | process-pipes-203 (seconds)    |    (I) -3.65% |
|                         | process-pipes-234 (seconds)    |    (I) -3.45% |
|                         | process-pipes-256 (seconds)    |    (I) -3.47% |
|                         | process-sockets-1 (seconds)    |         2.13% |
|                         | process-sockets-4 (seconds)    |         1.02% |
|                         | process-sockets-7 (seconds)    |        -0.26% |
|                         | process-sockets-12 (seconds)   |        -1.24% |
|                         | process-sockets-21 (seconds)   |         0.01% |
|                         | process-sockets-30 (seconds)   |        -0.15% |
|                         | process-sockets-48 (seconds)   |         0.15% |
|                         | process-sockets-79 (seconds)   |         1.45% |
|                         | process-sockets-110 (seconds)  |        -1.64% |
|                         | process-sockets-141 (seconds)  |    (I) -4.27% |
|                         | process-sockets-172 (seconds)  |         0.30% |
|                         | process-sockets-203 (seconds)  |        -1.71% |
|                         | process-sockets-234 (seconds)  |        -1.94% |
|                         | process-sockets-256 (seconds)  |        -0.71% |
|                         | thread-pipes-1 (seconds)       |         0.66% |
|                         | thread-pipes-4 (seconds)       |         1.66% |
|                         | thread-pipes-7 (seconds)       |        -0.17% |
|                         | thread-pipes-12 (seconds)      |    (I) -4.12% |
|                         | thread-pipes-21 (seconds)      |    (I) -2.13% |
|                         | thread-pipes-30 (seconds)      |    (I) -3.78% |
|                         | thread-pipes-48 (seconds)      |    (I) -5.77% |
|                         | thread-pipes-79 (seconds)      |    (I) -5.31% |
|                         | thread-pipes-110 (seconds)     |    (I) -6.12% |
|                         | thread-pipes-141 (seconds)     |    (I) -4.00% |
|                         | thread-pipes-172 (seconds)     |    (I) -3.01% |
|                         | thread-pipes-203 (seconds)     |    (I) -2.62% |
|                         | thread-pipes-234 (seconds)     |    (I) -2.00% |
|                         | thread-pipes-256 (seconds)     |    (I) -2.30% |
|                         | thread-sockets-1 (seconds)     |     (R) 2.39% |
+-------------------------+--------------------------------+---------------+

+-------------------------+------------------------------------------------+
| mmtests/sysbench-mutex  | sysbenchmutex-1 (usec)         |        -0.02% |
|                         | sysbenchmutex-4 (usec)         |        -0.02% |
|                         | sysbenchmutex-7 (usec)         |         0.00% |
|                         | sysbenchmutex-12 (usec)        |         0.12% |
|                         | sysbenchmutex-21 (usec)        |        -0.40% |
|                         | sysbenchmutex-30 (usec)        |         0.08% |
|                         | sysbenchmutex-48 (usec)        |         2.59% |
|                         | sysbenchmutex-79 (usec)        |        -0.80% |
|                         | sysbenchmutex-110 (usec)       |        -3.87% |
|                         | sysbenchmutex-128 (usec)       |    (I) -4.46% |
+-------------------------+--------------------------------+---------------+




      

        
 mm/khugepaged.c | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 4ec324a4c1fe..a0f1df2a7ae6 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -676,9 +676,7 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
 			writable = true;
 	}

-	if (unlikely(!writable)) {
-		result = SCAN_PAGE_RO;
-	} else if (unlikely(cc->is_khugepaged && !referenced)) {
+	if (unlikely(cc->is_khugepaged && !referenced)) {
 		result = SCAN_LACK_REFERENCED_PAGE;
 	} else {
 		result = SCAN_SUCCEED;
@@ -1421,9 +1419,7 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm,
 		     mmu_notifier_test_young(vma->vm_mm, _address)))
 			referenced++;
 	}
-	if (!writable) {
-		result = SCAN_PAGE_RO;
-	} else if (cc->is_khugepaged &&
+	if (cc->is_khugepaged &&
 		   (!referenced ||
 		    (unmapped && referenced < HPAGE_PMD_NR / 2))) {
 		result = SCAN_LACK_REFERENCED_PAGE;
@@ -2830,7 +2826,6 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start,
 		case SCAN_PMD_NULL:
 		case SCAN_PTE_NON_PRESENT:
 		case SCAN_PTE_UFFD_WP:
-		case SCAN_PAGE_RO:
 		case SCAN_LACK_REFERENCED_PAGE:
 		case SCAN_PAGE_NULL:
 		case SCAN_PAGE_COUNT:
--
2.30.2



      

      
I guess you delay the final cleanup so you can combine it with tracepoint
removal in next patch, not really sure why they're separate but meh not a
big deal.


    

  


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