Messages in this thread | | | Date | Wed, 02 Dec 2015 16:52:26 -0800 | From | "Shi, Yang" <> | Subject | Re: [PATCH V2 2/7] mm/gup: add gup trace points |
| |
On 12/2/2015 4:11 PM, Shi, Yang wrote: > On 12/2/2015 3:36 PM, Dave Hansen wrote: >> On 12/02/2015 02:53 PM, Yang Shi wrote: >>> diff --git a/mm/gup.c b/mm/gup.c >>> index deafa2c..10245a4 100644 >>> --- a/mm/gup.c >>> +++ b/mm/gup.c >>> @@ -13,6 +13,9 @@ >>> #include <linux/rwsem.h> >>> #include <linux/hugetlb.h> >>> >>> +#define CREATE_TRACE_POINTS >>> +#include <trace/events/gup.h> >>> + >>> #include <asm/pgtable.h> >>> #include <asm/tlbflush.h> >> >> This needs to be _the_ last thing that gets #included. Otherwise, you >> risk colliding with any other trace header that gets implicitly included >> below. > > Thanks for the suggestion, will move it to the last. > >> >>> @@ -1340,6 +1346,8 @@ int __get_user_pages_fast(unsigned long start, >>> int nr_pages, int write, >>> start, len))) >>> return 0; >>> >>> + trace_gup_get_user_pages_fast(start, nr_pages, write, pages); >>> + >>> /* >>> * Disable interrupts. We use the nested form as we can >>> already have >>> * interrupts disabled by get_futex_key. >> >> It would be _really_ nice to be able to see return values from the >> various gup calls as well. Is that feasible? > > I think it should be feasible. kmem_cache_alloc trace event could show > return value. I'm supposed gup trace events should be able to do the > same thing.
Just did a quick test, it is definitely feasible. Please check the below test log:
trace-cmd-200 [000] 99.221486: gup_get_user_pages: start=8000000ff0 nr_pages=1 ret=1 trace-cmd-200 [000] 99.223215: gup_get_user_pages: start=8000000fdb nr_pages=1 ret=1 trace-cmd-200 [000] 99.223298: gup_get_user_pages: start=8000000ed0 nr_pages=1 ret=1
nr_pages is the number of pages requested by the gup, ret is the return value.
If nobody has objection, I will add it into V3.
Regards, Yang
> > Regards, > Yang > >> >
| |