Messages in this thread | | | Date | Mon, 27 Feb 2006 17:16:47 -0500 | From | Shailabh Nagar <> | Subject | Re: [Patch 6/7] Swapin page fault delays |
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Arjan van de Ven wrote:
>On Mon, 2006-02-27 at 03:22 -0500, Shailabh Nagar wrote: > > >>delayacct-swapin.patch >> >>Record time spent by a task waiting for its pages to be swapped in. >>This statistic can help in adjusting the rss limits of >>tasks (process), especially relative to each other, when the system is >>under memory pressure. >> >> > > >ok this poses a question: how do you deal with nested timings? > I don't :-( An earlier version used local variables instead of one within the task_delay_info struct but we moved to using a var within to save on stack space in critical paths.
>Say an >O_SYC write which internally causes a pagefault? > > And here we hit the problem of nesting being needed....so....
>delayacct_timestamp_start() at minimum has to get event-type specific, >or even implement a stack of some sorts. > > Would keeping the timespec vars on the stacks of the functions being accounted be too expensive vs. keeping bunches of vars within task_delay_info to deal with the nesting ?
Unfortunately, the need for accuracy also means the variables needed are timespecs and not something smaller.
--Shailabh
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