On 03/02/2011 04:45 PM, Ingo Molnar wrote:
* Liu Yuan<namei.unix@xxxxxxxxx> wrote:
+ if (likely(!retry_find)&& page&& PageUptodate(page))
+ page_cache_acct_hit(inode->i_sb, READ);
+ else
+ page_cache_acct_missed(inode->i_sb, READ);
Sigh.
This would make such a nice tracepoint or sw perf event. It could be collected in a
'count' form, equivalent to the stats you are aiming for here, or it could even be
traced, if someone is interested in such details.
It could be mixed with other events, enriching multiple apps at once.
But, instead of trying to improve those aspects of our existing instrumentation
frameworks, mm/* is gradually growing its own special instrumentation hacks, missing
the big picture and fragmenting the instrumentation space some more.
Thanks for the quick response. Actually our team(including Liu) here are
planing to add some
debug info to the mm parts for analyzing the application behavior and
hope to find some way
to improve our application's performance.
We have searched the trace points in mm, but it seems to us that the
trace points isn't quite welcomed
there. Only vmscan and writeback have some limited trace points added.
That's the reason we first
tried to add some debug info like this patch. You does shed some light
on our direction. Thanks.
btw, what part do you think is needed to add some trace point? We
volunteer to add more if you like.
Regards,
Tao
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