Re: Question of backporting the trace-vmscan-postprocess.pl

[Ying Han <yinghan@google.com>]

On Tue, Aug 31, 2010 at 12:53 AM, Mel Gorman <mel@csn.ul.ie> wrote:
> On Mon, Aug 30, 2010 at 04:10:05PM -0700, Ying Han wrote:
>> Hi Mel:
>>
>> I've been looking into the vmscan:tracing you added for 2.6.36_rc1. I
>> also backported into 2.6.34 which is the kernel we are currently
>> working on. However, I seems can not get it fully functional. Are you
>> aware of any changes on the kernel tracing ABI which could cause that
>> ?
>>
>
> Nothing springs to mind but ...
>
>> Here is how I reproduce it and I also attached the
>> postprocess/trace-vmscan-postprocess.pl I patched.
>>
>> # mount -t debugfs nodev /sys/kernel/debug/
>>
>> # for i in `find /sys/kernel/debug/tracing/events -name "enable" |
>> grep mm_`; do echo 1 > $i; done
>>
>> run a process with pid==30196
>>
>> # echo 'common_pid == 30196' > /sys/kernel/debug/tracing/events/vmscan/filter
>>
>> # cat /sys/kernel/debug/tracing/events/vmscan/filter
>> common_pid == 30196
>>
>> # ./trace-vmscan-postprocess.pl < /sys/kernel/debug/tracing/trace_pipe
>> WARNING: Event vmscan/mm_vmscan_lru_shrink_inactive format string not found
>> WARNING: Event vmscan/mm_vmscan_lru_shrink_active format string not found
>> ^CSIGINT received, report pending. Hit ctrl-c again to exit
>>
>
> I didn't test the script for live processing. I was logging
> /sys/kernel/debug/tracing/trace_pipe to a file and post-processing it
> after a test. I suggest you do the same and check if any events for pid
> 30196 were recorded.

Ok. I tried the logging and it works better this time. Both pagealloc
and vmscan give me some data
with the filtering works ok. thanks for your replay :)

--Ying

>> Reclaim latencies expressed as order-latency_in_ms
>>
>> Process          Direct     Wokeup      Pages      Pages    Pages
>> Time
>> details           Rclms     Kswapd    Scanned    Sync-IO ASync-IO
>> Stalled
>>
>> Kswapd           Kswapd      Order      Pages      Pages    Pages
>> Instance        Wakeups  Re-wakeup    Scanned    Sync-IO ASync-IO
>>
>> Summary
>> Direct reclaims:
>> Direct reclaim pages scanned:
>> Direct reclaim write file sync I/O:
>> Direct reclaim write anon sync I/O:
>> Direct reclaim write file async I/O:
>> Direct reclaim write anon async I/O:
>> Wake kswapd requests:
>> Time stalled direct reclaim:          0.00 seconds
>>
>> Kswapd wakeups:
>> Kswapd pages scanned:
>> Kswapd reclaim write file sync I/O:
>> Kswapd reclaim write anon sync I/O:
>> Kswapd reclaim write file async I/O:
>> Kswapd reclaim write anon async I/O:
>> Time kswapd awake:                    0.00 seconds
>>
>> So it didn't give me any output. However, if I turn off the filter for
>> vmscan, it did give me some data but with random processes on the
>> system.
>>
>
> Did one of them processes include 30196 that you were filtering for?
>
>> The same set of tests works for trace-pagealloc-postprocess.pl though
>>
>> # cat /sys/kernel/debug/tracing/events/kmem/filter
>> common_pid == 30196
>>
>> # ./trace-pagealloc-postprocess.pl < /sys/kernel/debug/tracing/trace_pipe
>>
>> Process           Pages      Pages      Pages    Pages       PCPU
>> PCPU     PCPU   Fragment Fragment  MigType Fragment Fragment  Unknown
>> details          allocd     allocd      freed    freed      pages
>> drains  refills   Fallback  Causing  Changed   Severe Moderate
>>                         under lock     direct  pagevec      drain
>> -30196             2871       2917          0        0          0
>>   0      439         32       32        0       32        0        0
>> ddtest-30196       4560       4328          0        0          0
>>   0      639         26       26        1       25        1        0
>>
>
> Maybe there were page allocator events and not vmscan events?
>
> --
> Mel Gorman
> Part-time Phd Student                          Linux Technology Center
> University of Limerick                         IBM Dublin Software Lab
>

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