lkml.org 
[lkml]   [2016]   [Jan]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [RFC V5] Add gup trace points support
From
Date
Hi Steven,

Any more comments on this series? How should I proceed it?

Thanks,
Yang


On 12/9/2015 1:22 PM, Yang Shi wrote:
> v5:
> * Fixed a typo introduced by v4 rebase
> * Removed redundant "#define CREATE_TRACE_POINTS" from architecture specifc
> gup.c
>
> v4:
> * Adopted Steven's suggestion to use "unsigned int" for nr_pages to save
> space in ring buffer since it is unlikely to have more than 0xffffffff
> pages are touched by gup in one invoke
> * Remove unnecessray type cast
>
> v3:
> * Adopted suggestion from Dave Hansen to move the gup header include to the last
> * Adopted comments from Steven:
> - Use DECLARE_EVENT_CLASS and DEFINE_EVENT
> - Just keep necessary TP_ARGS
> * Moved archtichture specific fall-backable fast version trace point after the
> do while loop since it may jump to the slow version.
> * Not implement recording return value since Steven plans to have it in generic
> tracing code
>
> v2:
> * Adopted commetns from Steven
> - remove all reference to tsk->comm since it is unnecessary for non-sched
> trace points
> - reduce arguments for __get_user_pages trace point and update mm/gup.c
> accordingly
> * Added Ralf's acked-by for patch 4/7.
>
>
> Some background about why I think this might be useful.
>
> When I was profiling some hugetlb related program, I got page-faults event
> doubled when hugetlb is enabled. When I looked into the code, I found page-faults
> come from two places, do_page_fault and gup. So, I tried to figure out which
> play a role (or both) in my use case. But I can't find existing finer tracing
> event for sub page-faults in current mainline kernel.
>
> So, I added the gup trace points support to have finer tracing events for
> page-faults. The below events are added:
>
> __get_user_pages
> __get_user_pages_fast
> fixup_user_fault
>
> Both __get_user_pages and fixup_user_fault call handle_mm_fault.
>
> Just added trace points to raw version __get_user_pages since all variants
> will call it finally to do real work.
>
> Although __get_user_pages_fast doesn't call handle_mm_fault, it might be useful
> to have it to distinguish between slow and fast version.
>

\
 
 \ /
  Last update: 2016-01-12 21:41    [W:0.106 / U:2.328 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site