Messages in this thread | | | From | Namhyung Kim <> | Subject | Re: perf support user-space hw_breakpoint? | Date | Thu, 28 Jun 2012 11:20:09 +0900 |
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On Thu, 28 Jun 2012 09:02:02 +0800, Jovi Zhang wrote: > On Mon, Jun 25, 2012 at 4:26 PM, Namhyung Kim <namhyung@kernel.org> wrote: >> BTW, when I perf record on a hwbp, it failed with ENOSPC. >> I guess it's because each per-task-per-cpu event tried to >> create an event so it'd get more than supported by h/w. >> The strace told me that the fifth call to perf_event_open >> failed on my 6-core machine. >> > I have same result as you in my linux box. > This should be a bug cause by commit d1cb9f(perf target: Add uses_mmap field) > > Namhyung, How about below patch? >
NAK. This uses_mmap field is needed to setup per-task-per-cpu events for perf record (mostly). Without it, perf suffered from severe scalability issues. Maybe we can change it not to create per-task-per-cpu events iff for hwbp events only, but I'm not sure it's the right thing.
Thanks, Namhyung
> > From 4b77b99df9ca3b99be4ccf8c4256e622aae9203f Mon Sep 17 00:00:00 2001 > From: Jovi Zhang <bookjovi@gmail.com> > Date: Thu, 28 Jun 2012 07:49:41 +0800 > Subject: [PATCH] perf: revert commit d1cb9f(perf target: Add uses_mmap field) > > In my x86 4 cores cpu linux machine, using hw_breakpoint output as follows: > > Before add uses_mmap field: > [root@jovi perf]# ./perf record -g -e mem:0x080652c8 -e mem:0x1098 -- > /usr/bin/ls >/dev/null > [ perf record: Woken up 1 times to write data ] > [ perf record: Captured and wrote 0.015 MB perf.data (~640 samples) ] > > After add uses_mmap field: > [root@jovi perf]# ./perf record -e mem:0x080652c8 -e mem:0x1098 -- > /usr/bin/ls >/dev/null > Error: sys_perf_event_open() syscall returned with 28 (No space > left on device). /bin/dmesg may provide additional information. > > Fatal: No CONFIG_PERF_EVENTS=y kernel support configured? > > Adding uses_mmap field in target structure will cause perf-record > creat per-task-per-cpu > event for each evsel, this will break hw_breakpoint(have limit debug > registers in cpu), > in above example, we should create dummy cpumap for hw_breakpoint > event, not per-task-per-cpu, > fix it. > > Noticed-by: Namhyung Kim <namhyung@kernel.org> > Signed-off-by: Jovi Zhang <bookjovi@gmail.com> > --- > tools/perf/builtin-record.c | 3 --- > tools/perf/builtin-test.c | 1 - > tools/perf/builtin-top.c | 3 --- > tools/perf/util/evlist.c | 4 +--- > tools/perf/util/target.h | 1 - > 5 files changed, 1 insertion(+), 11 deletions(-) > > diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c > index f95840d..8128213 100644 > --- a/tools/perf/builtin-record.c > +++ b/tools/perf/builtin-record.c > @@ -754,9 +754,6 @@ static struct perf_record record = { > .user_freq = UINT_MAX, > .user_interval = ULLONG_MAX, > .freq = 4000, > - .target = { > - .uses_mmap = true, > - }, > }, > .write_mode = WRITE_FORCE, > .file_new = true, > diff --git a/tools/perf/builtin-test.c b/tools/perf/builtin-test.c > index 5a8727c..338a0cc 100644 > --- a/tools/perf/builtin-test.c > +++ b/tools/perf/builtin-test.c > @@ -647,7 +647,6 @@ static int test__PERF_RECORD(void) > struct perf_record_opts opts = { > .target = { > .uid = UINT_MAX, > - .uses_mmap = true, > }, > .no_delay = true, > .freq = 10, > diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c > index 6bb0277..cc78e06 100644 > --- a/tools/perf/builtin-top.c > +++ b/tools/perf/builtin-top.c > @@ -1165,9 +1165,6 @@ int cmd_top(int argc, const char **argv, const > char *prefix __used) > .freq = 4000, /* 4 KHz */ > .mmap_pages = 128, > .sym_pcnt_filter = 5, > - .target = { > - .uses_mmap = true, > - }, > }; > char callchain_default_opt[] = "fractal,0.5,callee"; > const struct option options[] = { > diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c > index 7400fb3..e791029 100644 > --- a/tools/perf/util/evlist.c > +++ b/tools/perf/util/evlist.c > @@ -622,9 +622,7 @@ int perf_evlist__create_maps(struct perf_evlist *evlist, > if (evlist->threads == NULL) > return -1; > > - if (perf_target__has_task(target)) > - evlist->cpus = cpu_map__dummy_new(); > - else if (!perf_target__has_cpu(target) && !target->uses_mmap) > + if (perf_target__has_task(target) || !perf_target__has_cpu(target)) > evlist->cpus = cpu_map__dummy_new(); > else > evlist->cpus = cpu_map__new(target->cpu_list); > diff --git a/tools/perf/util/target.h b/tools/perf/util/target.h > index a4be857..c43f632 100644 > --- a/tools/perf/util/target.h > +++ b/tools/perf/util/target.h > @@ -11,7 +11,6 @@ struct perf_target { > const char *uid_str; > uid_t uid; > bool system_wide; > - bool uses_mmap; > }; > > enum perf_target_errno { > -- > 1.7.9.7 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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