Hello,
(02/15/10 22:22), KOSAKI Motohiro wrote:
>>> Here is a scratch patch to exercise the "object collections" idea :)
>>>
>>> Interestingly, the pagecache walk is pretty fast, while copying out the trace
>>> data takes more time:
>>>
>>> # time (echo / > walk-fs)
>>> (; echo / > walk-fs; ) 0.01s user 0.11s system 82% cpu 0.145 total
>>>
>>> # time wc /debug/tracing/trace
>>> 4570 45893 551282 /debug/tracing/trace
>>> wc /debug/tracing/trace 0.75s user 0.55s system 88% cpu 1.470 total
>>
>> Ah got it: it takes much time to "print" the raw trace data.
>>
>>> TODO:
>>>
>>> correctness
>>> - show file path name
>>> XXX: can trace_seq_path() be called directly inside TRACE_EVENT()?
>>
>> OK, finished with the file name with d_path(). I choose not to mangle
>> the possible '\n' in file names, and simply show "?" for such files,
>> for the sake of speed.
>
>
> This patch is nicer than KII-san's one. I plan to test it on
> my local test environment awhile.
I don't think my patch is completely replaced by Wu's patch.
Both patches focus on pagecache and will work together for achieving
perf enhancement for mm like "perf mm".
His patch can efficiently dump a pagecache usage snapshot for a file system
or a file as he said.
And we will be able to just monitor pagecache increase and decrease
by taking some snapshots for pagecache using his patch.
My patch can monitor some pagecache behavior like pagecache hit ratio and
using frequency(e.g. the following outputs).
For example, the outputs shows yum's pagecache behavior analysis using my patch.
Please focus on inode 16 and 778 on the device(253:0).
The system has 5752 pagecaches for the inode 16 and 86 pagecaches for
the inode 778.
We will be able to know same information using his patch as well.
But we can get further detailed information about pagecache in the system
using my patch.
There is a big difference of using frequency between inode 16 and inode 778.
The inode 16 is used by the yum more same pagecaches than inode 778's.
And maybe it is useful to improve/tune pagecache management like pdflush.
[process list]
o yum-3215
cache find cache hit cache hit
device inode count count ratio
--------------------------------------------------------
253:0 16 34434 34130 99.12%
253:0 198 9692 9463 97.64%
253:0 639 647 628 97.06%
253:0 778 32 29 90.62%
253:0 7305 50225 49005 97.57%
253:0 144217 12 10 83.33%
253:0 262775 16 13 81.25%
*snip*
[file list]
device cached
(maj:min) inode pages
--------------------------------
253:0 16 5752
253:0 198 2233
253:0 639 51
253:0 778 86
253:0 7305 12307
253:0 144217 11
253:0 262775 39
*snip*
[process list]
o yum-3215
device cached added removed indirect
(maj:min) inode pages pages pages removed pages
----------------------------------------------------------------
253:0 16 34130 5752 0 0
253:0 198 9463 2233 0 0
253:0 639 628 51 0 0
253:0 778 29 78 0 0
253:0 7305 49005 12307 0 0
253:0 144217 10 11 0 0
253:0 262775 13 39 0 0
*snip*
----------------------------------------------------------------
total: 102346 26165 1 0
Any comments are welcome.
Thanks,
Keiichi
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