From: Luigi Semenzato <semenzato@google.com>
To: linux-mm@kvack.org, Minchan Kim <minchan@kernel.org>,
Dan Magenheimer <dan.magenheimer@oracle.com>
Subject: Re: behavior of zram stats, and zram allocation limit
Date: Wed, 21 Nov 2012 16:46:02 -0800 [thread overview]
Message-ID: <CAA25o9Su0Wppnwug3xwAgpYNnmtJjJsrdjj3QqqU76oXkJi6iw@mail.gmail.com> (raw)
In-Reply-To: <CAA25o9Q4gMPeLf3uYJzMNR1EU4D3OPeje24X4PNsUVHGoqyY5g@mail.gmail.com>
My apologies---what I am seeing is actually reasonable. My synthetic
load mistakenly was only touching the pages with incompressible data
in them. Thus it's reasonable that the compression ratio improves,
since those pages are brought back in, and the zero pages are pushed
out. :-(
On Wed, Nov 21, 2012 at 2:58 PM, Luigi Semenzato <semenzato@google.com> wrote:
> Hi,
>
> Two questions for zram developers/users. (Please let me know if it is
> NOT acceptable to use this list for these questions.)
>
> 1. When I run a synthetic load using zram from kernel 3.4.0,
> compr_data_size from /sys/block/zram0 seems to decrease even though
> orig_data_size stays constant (see below). Is this a bug that was
> fixed in a later release? (The synthetic load is a bunch of processes
> that allocate memory, fill half of it with data from /dev/urandom, and
> touch the memory randomly.) I looked at the code and it looks right.
> :-P
>
> 2. Is there a way of setting the max amount of RAM that zram is
> allowed to allocate? Right now I can set the size of the
> *uncompressed* swap device, but how much memory gets allocated depends
> on the compression ratio, which could vary.
>
> Thanks!
>
>
> localhost ~ # ./zraminfo
> compr_data_size: 220570516 (210 MB)
> disksize: 3101462528 (2957 MB)
> mem_used_total: 230383616 (219 MB)
> notify_free: 1553 (0 MB)
> num_reads: 6093 (0 MB)
> num_writes: 150955 (0 MB)
> orig_data_size: 599126016 (571 MB)
> size: 6057544 (5 MB)
> zero_pages: 4040 (0 MB)
> eff. compr. ratio: 2.50
> localhost ~ #
> localhost ~ # ./zraminfo
> compr_data_size: 208845619 (199 MB)
> disksize: 3101462528 (2957 MB)
> mem_used_total: 213528576 (203 MB)
> notify_free: 76808 (0 MB)
> num_reads: 81918 (0 MB)
> num_writes: 202924 (0 MB)
> orig_data_size: 586076160 (558 MB)
> size: 6057544 (5 MB)
> zero_pages: 7434 (0 MB)
> eff. compr. ratio: 2.80
> localhost ~ # ./zraminfo
> compr_data_size: 205964814 (196 MB)
> disksize: 3101462528 (2957 MB)
> mem_used_total: 210976768 (201 MB)
> notify_free: 91823 (0 MB)
> num_reads: 105170 (0 MB)
> num_writes: 218485 (0 MB)
> orig_data_size: 614526976 (586 MB)
> size: 6057544 (5 MB)
> zero_pages: 8666 (0 MB)
> eff. compr. ratio: 2.98
> localhost ~ # ./zraminfo
> compr_data_size: 229739564 (219 MB)
> disksize: 3101462528 (2957 MB)
> mem_used_total: 235798528 (224 MB)
> notify_free: 108381 (0 MB)
> num_reads: 147372 (0 MB)
> num_writes: 251829 (0 MB)
> orig_data_size: 697163776 (664 MB)
> size: 6057544 (5 MB)
> zero_pages: 9972 (0 MB)
> eff. compr. ratio: 3.01
> localhost ~ # ./zraminfo
> compr_data_size: 229458612 (218 MB)
> disksize: 3101462528 (2957 MB)
> mem_used_total: 234651648 (223 MB)
> notify_free: 132169 (0 MB)
> num_reads: 203970 (0 MB)
> num_writes: 282732 (0 MB)
> orig_data_size: 751472640 (716 MB)
> size: 6057544 (5 MB)
> zero_pages: 11139 (0 MB)
> eff. compr. ratio: 3.27
> localhost ~ # ./zraminfo
> compr_data_size: 217296398 (207 MB)
> disksize: 3101462528 (2957 MB)
> mem_used_total: 222715904 (212 MB)
> notify_free: 151071 (0 MB)
> num_reads: 243898 (0 MB)
> num_writes: 302316 (0 MB)
> orig_data_size: 778227712 (742 MB)
> size: 6057544 (5 MB)
> zero_pages: 10195 (0 MB)
> eff. compr. ratio: 3.58
> localhost ~ # ./zraminfo
> compr_data_size: 221631885 (211 MB)
> disksize: 3101462528 (2957 MB)
> mem_used_total: 227188736 (216 MB)
> notify_free: 166323 (0 MB)
> num_reads: 278621 (0 MB)
> num_writes: 323811 (0 MB)
> orig_data_size: 821809152 (783 MB)
> size: 6057544 (5 MB)
> zero_pages: 10737 (0 MB)
> eff. compr. ratio: 3.70
> localhost ~ # ./zraminfo
> compr_data_size: 216354938 (206 MB)
> disksize: 3101462528 (2957 MB)
> mem_used_total: 221990912 (211 MB)
> notify_free: 182529 (0 MB)
> num_reads: 322923 (0 MB)
> num_writes: 342028 (0 MB)
> orig_data_size: 849281024 (809 MB)
> size: 6057544 (5 MB)
> zero_pages: 10990 (0 MB)
> eff. compr. ratio: 3.92
> localhost ~ # ./zraminfo
> compr_data_size: 163852068 (156 MB)
> disksize: 3101462528 (2957 MB)
> mem_used_total: 170209280 (162 MB)
> notify_free: 212669 (0 MB)
> num_reads: 358680 (0 MB)
> num_writes: 342896 (0 MB)
> orig_data_size: 777981952 (741 MB)
> size: 6057544 (5 MB)
> zero_pages: 7466 (0 MB)
> eff. compr. ratio: 4.77
> localhost ~ # ./zraminfo
> compr_data_size: 164434814 (156 MB)
> disksize: 3101462528 (2957 MB)
> mem_used_total: 170631168 (162 MB)
> notify_free: 218105 (0 MB)
> num_reads: 368430 (0 MB)
> num_writes: 349043 (0 MB)
> orig_data_size: 785846272 (749 MB)
> size: 6057544 (5 MB)
> zero_pages: 7996 (0 MB)
> eff. compr. ratio: 4.78
> localhost ~ # ./zraminfo
> compr_data_size: 129945717 (123 MB)
> disksize: 3101462528 (2957 MB)
> mem_used_total: 136237056 (129 MB)
> notify_free: 241461 (0 MB)
> num_reads: 404654 (0 MB)
> num_writes: 360153 (0 MB)
> orig_data_size: 763969536 (728 MB)
> size: 6057544 (5 MB)
> zero_pages: 7911 (0 MB)
> eff. compr. ratio: 5.88
> localhost ~ # ./zraminfo
> compr_data_size: 134384535 (128 MB)
> disksize: 3101462528 (2957 MB)
> mem_used_total: 140816384 (134 MB)
> notify_free: 242365 (0 MB)
> num_reads: 406159 (0 MB)
> num_writes: 362829 (0 MB)
> orig_data_size: 773607424 (737 MB)
> size: 6057544 (5 MB)
> zero_pages: 7975 (0 MB)
> eff. compr. ratio: 5.69
> localhost ~ # ./zraminfo
> compr_data_size: 133314196 (127 MB)
> disksize: 3101462528 (2957 MB)
> mem_used_total: 139538432 (133 MB)
> notify_free: 252447 (0 MB)
> num_reads: 411617 (0 MB)
> num_writes: 365459 (0 MB)
> orig_data_size: 754352128 (719 MB)
> size: 6057544 (5 MB)
> zero_pages: 7954 (0 MB)
> eff. compr. ratio: 5.68
> localhost ~ # ./zraminfo
> compr_data_size: 124826153 (119 MB)
> disksize: 3101462528 (2957 MB)
> mem_used_total: 131440640 (125 MB)
> notify_free: 263839 (0 MB)
> num_reads: 427837 (0 MB)
> num_writes: 375085 (0 MB)
> orig_data_size: 762548224 (727 MB)
> size: 6057544 (5 MB)
> zero_pages: 7504 (0 MB)
> eff. compr. ratio: 6.08
> localhost ~ # ./zraminfo
> compr_data_size: 94379398 (90 MB)
> disksize: 3101462528 (2957 MB)
> mem_used_total: 105000960 (100 MB)
> notify_free: 291596 (0 MB)
> num_reads: 465420 (0 MB)
> num_writes: 386267 (0 MB)
> orig_data_size: 721780736 (688 MB)
> size: 6057544 (5 MB)
> zero_pages: 7482 (0 MB)
> eff. compr. ratio: 7.31
> localhost ~ # ./zraminfo
> compr_data_size: 67124988 (64 MB)
> disksize: 3101462528 (2957 MB)
> mem_used_total: 73981952 (70 MB)
> notify_free: 336548 (0 MB)
> num_reads: 499935 (0 MB)
> num_writes: 400298 (0 MB)
> orig_data_size: 700309504 (667 MB)
> size: 6057544 (5 MB)
> zero_pages: 7495 (0 MB)
> eff. compr. ratio: 10.41
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next prev parent reply other threads:[~2012-11-22 0:46 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-21 22:58 Luigi Semenzato
2012-11-22 0:46 ` Luigi Semenzato [this message]
2012-11-23 5:51 ` Minchan Kim
2012-11-23 16:45 ` Dan Magenheimer
2012-11-23 17:56 ` Luigi Semenzato
2013-02-17 3:25 ` Jaegeuk Hanse
2013-02-19 23:54 ` Minchan Kim
2013-02-17 3:01 ` Jaegeuk Hanse
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