2011/3/15 Mulyadi Santosa <mulyadi.santosa@xxxxxxxxx>
Hi Minwoo...
I am not the best... just trying to give idea here...
basic question is: are you sure the cache misses you see during
On Tue, Mar 15, 2011 at 00:03, Minwoo Lee <ermaker@xxxxxxxxx> wrote:
> Hello.
> I am hacking the kernel source for studying.
> I just modified schedule() in kernel/sched.c for profiling processes.
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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