Thanks for reply. 2011/3/15 Mulyadi Santosa <mulyadi.sant...@gmail.com>
> Hi Minwoo... > > I am not the best... just trying to give idea here... > > On Tue, Mar 15, 2011 at 00:03, Minwoo Lee <erma...@gmail.com> wrote: > > Hello. > > I am hacking the kernel source for studying. > > I just modified schedule() in kernel/sched.c for profiling processes. > > > basic question is: are you sure the cache misses you see during > schedule is entirely attributed to the soon-to-be-switched-out > process? have you consider that during that process run time, on going > interrupts/exception etc could attribute into the cache misses? > You're right. This code is wrong. I wrote the code just for checking that the perf library runs. The code should be changed to check cache misses while in a slice time(or an unit time?). The main problem is, sys_pref_event_open does not return the valid fd. I have no idea why sys_perf_event_open returns invalid fd. > > and about this line: > BUG_ON(res != sizeof(u64)) > > not sure if I read it correctly, but previously I see "res" is > declared as size_t, right? > Yes, res is declared as size_t. Also type of sizeof() is size_t. Isn't it right? This line assumes that sys_read() read correctly. This line is from the code in line 227 at tools/perf/builtin-stat.c, 225 res = read(fd[cpu][counter][thread], 226 single_count, nv * sizeof(u64)); 227 assert(res == nv * sizeof(u64)); > > > > -- > regards, > > Mulyadi Santosa > Freelance Linux trainer and consultant > > blog: the-hydra.blogspot.com > training: mulyaditraining.blogspot.com >
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