Messages in this thread | | | Subject | Re: [RFC V5] Add gup trace points support | From | "Shi, Yang" <> | Date | Tue, 12 Jan 2016 12:00:54 -0800 |
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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. >
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