Re: [PATCHSET 0/7] perf kmem: Implement page allocation analysis (v5)

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Fri, Mar 27, 2015 at 11:08:00AM +0900, Namhyung Kim escreveu:
> Hello,
> 
> Currently perf kmem command only analyzes SLAB memory allocation.  And
> I'd like to introduce page allocation analysis also.  Users can use
>  --slab and/or --page option to select it.  If none of these options
> are used, it does slab allocation analysis for backward compatibility.
> 
>  * changes in v5)
>   - print migration type and gfp flags in more compact form (Arnaldo)
>   - add kmem.default config option

Ok, I'll try this after lunch and if nobody else has any more issues
with it, merge it, OK? Ingo?

- Arnaldo
 
> * changes in v4)
>   - use pfn instead of struct page * in tracepoints  (Joonsoo, Ingo)
>   - print gfp flags in human readable string  (Joonsoo, Minchan)
> 
> * changes in v3)
>   - add live page statistics
> 
>  * changes in v2)
>   - Use thousand grouping for big numbers - i.e. 12345 -> 12,345  (Ingo)
>   - Improve output stat readability  (Ingo)
>   - Remove alloc size column as it can be calculated from hits and order
> 
> Patch 1 is to convert tracepoint to save pfn instead of struct page *.
> Patch 2 implements basic support for page allocation analysis, patch 3
> deals with the callsite and patch 4 implements sorting.  Patch 5
> introduces live page analysis which is to focus on currently allocated
> pages only.  Patch 6 prints gfp flags in human readable string and
> patch 7 adds kmem.default config option to be able to select page
> analysis by default.
> 
> In this patchset, I used two kmem events: kmem:mm_page_alloc and
> kmem_page_free for analysis as they can track almost all of memory
> allocation/free path AFAIK.  However, unlike slab tracepoint events,
> those page allocation events don't provide callsite info directly.  So
> I recorded callchains and extracted callsites like below:
> 
> Normal page allocation callchains look like this:
> 
>   360a7e __alloc_pages_nodemask
>   3a711c alloc_pages_current
>   357bc7 __page_cache_alloc   <-- callsite
>   357cf6 pagecache_get_page
>    48b0a prepare_pages
>    494d3 __btrfs_buffered_write
>    49cdf btrfs_file_write_iter
>   3ceb6e new_sync_write
>   3cf447 vfs_write
>   3cff99 sys_write
>   7556e9 system_call
>     f880 __write_nocancel
>    33eb9 cmd_record
>    4b38e cmd_kmem
>    7aa23 run_builtin
>    27a9a main
>    20800 __libc_start_main
> 
> But first two are internal page allocation functions so it should be
> skipped.  To determine such allocation functions, I used following regex:
> 
>   ^_?_?(alloc|get_free|get_zeroed)_pages?
> 
> This gave me a following list of functions (you can see this with -v):
> 
>   alloc func: __get_free_pages
>   alloc func: get_zeroed_page
>   alloc func: alloc_pages_exact
>   alloc func: __alloc_pages_direct_compact
>   alloc func: __alloc_pages_nodemask
>   alloc func: alloc_page_interleave
>   alloc func: alloc_pages_current
>   alloc func: alloc_pages_vma
>   alloc func: alloc_page_buffers
>   alloc func: alloc_pages_exact_nid
> 
> After skipping those function, it got '__page_cache_alloc'.
> 
> Other information such as allocation order, migration type and gfp
> flags are provided by tracepoint events.
> 
> Basically the output will be sorted by total allocation bytes, but you
> can change it by using -s/--sort option.  The following sort keys are
> added to support page analysis: page, order, mtype, gfp.  Existing
> 'callsite', 'bytes' and 'hit' sort keys also can be used.
> 
> An example follows:
> 
>   # perf kmem record --page sleep 5
>   [ perf record: Woken up 2 times to write data ]
>   [ perf record: Captured and wrote 1.065 MB perf.data (2949 samples) ]
> 
>   # perf kmem stat --page
>   # GFP flags
>   # ---------
>   # 00000010:         NI: GFP_NOIO
>   # 000000d0:          K: GFP_KERNEL
>   # 00000200:        NWR: GFP_NOWARN
>   # 000052d0: K|NWR|NR|C: GFP_KERNEL|GFP_NOWARN|GFP_NORETRY|GFP_COMP
>   # 000084d0:      K|R|Z: GFP_KERNEL|GFP_REPEAT|GFP_ZERO
>   # 000200d0:          U: GFP_USER
>   # 000200d2:         HU: GFP_HIGHUSER
>   # 000200da:        HUM: GFP_HIGHUSER_MOVABLE
>   # 000280da:      HUM|Z: GFP_HIGHUSER_MOVABLE|GFP_ZERO
>   # 002084d0:   K|R|Z|NT: GFP_KERNEL|GFP_REPEAT|GFP_ZERO|GFP_NOTRACK
>   # 0102005a:    NF|HW|M: GFP_NOFS|GFP_HARDWALL|GFP_MOVABLE
>   
>   ---------------------------------------------------------------------------------------------------------
>    Total alloc (KB) | Hits      | Order | Mig.type | GFP flags  | Callsite
>   ---------------------------------------------------------------------------------------------------------
>               3,876 |       969 |     0 |  MOVABLE | HUM        | shmem_alloc_page
>                 972 |       243 |     0 | UNMOVABL | K          | __pollwait
>                 624 |       156 |     0 |  MOVABLE | NF|HW|M    | __page_cache_alloc
>                 304 |        76 |     0 | UNMOVABL | U          | dma_generic_alloc_coherent
>                 108 |        27 |     0 |  MOVABLE | HUM|Z      | handle_mm_fault
>                  56 |        14 |     0 | UNMOVABL | K|R|Z|NT   | pte_alloc_one
>                  24 |         6 |     0 |  MOVABLE | HUM        | do_wp_page
>                  24 |         3 |     1 | UNMOVABL | K|NWR|NR|C | alloc_skb_with_frags
>                  16 |         4 |     0 | UNMOVABL | NWR        | __tlb_remove_page
>                  16 |         4 |     0 |  MOVABLE | HUM        | do_cow_fault
>    ...              | ...       | ...   | ...      | ...        | ...
>   ---------------------------------------------------------------------------------------------------------
>   
>   SUMMARY (page allocator)
>   ========================
>   Total allocation requests     :            1,518   [            6,096 KB ]
>   Total free requests           :            1,431   [            5,748 KB ]
>   
>   Total alloc+freed requests    :            1,330   [            5,344 KB ]
>   Total alloc-only requests     :              188   [              752 KB ]
>   Total free-only requests      :              101   [              404 KB ]
>   
>   Total allocation failures     :                0   [                0 KB ]
>   
>   Order     Unmovable   Reclaimable       Movable      Reserved  CMA/Isolated
>   -----  ------------  ------------  ------------  ------------  ------------
>       0           351             .         1,163             .             .
>       1             3             .             .             .             .
>       2             1             .             .             .             .
>       3             .             .             .             .             .
>       4             .             .             .             .             .
>       5             .             .             .             .             .
>       6             .             .             .             .             .
>       7             .             .             .             .             .
>       8             .             .             .             .             .
>       9             .             .             .             .             .
>      10             .             .             .             .             .
> 
> 
> I have some idea how to improve it.  But I'd also like to hear other
> idea, suggestion, feedback and so on.
> 
> This is available at perf/kmem-page-v5 branch on my tree:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git
> 
> Thanks,
> Namhyung
> 
> 
> Namhyung Kim (7):
>   tracing, mm: Record pfn instead of pointer to struct page
>   perf kmem: Analyze page allocator events also
>   perf kmem: Implement stat --page --caller
>   perf kmem: Support sort keys on page analysis
>   perf kmem: Add --live option for current allocation stat
>   perf kmem: Print gfp flags in human readable string
>   perf kmem: Add kmem.default config option
> 
>  include/trace/events/filemap.h         |    8 +-
>  include/trace/events/kmem.h            |   42 +-
>  include/trace/events/vmscan.h          |    8 +-
>  tools/perf/Documentation/perf-kmem.txt |   19 +-
>  tools/perf/builtin-kmem.c              | 1298 ++++++++++++++++++++++++++++++--
>  5 files changed, 1288 insertions(+), 87 deletions(-)
> 
> -- 
> 2.3.4

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