Messages in this thread Patch in this message | | | Date | Thu, 28 Jun 2012 09:02:02 +0800 | Subject | Re: perf support user-space hw_breakpoint? | From | Jovi Zhang <> |
| |
Hi
On Mon, Jun 25, 2012 at 4:26 PM, Namhyung Kim <namhyung@kernel.org> wrote: > Hi, Jovi > > On Mon, 25 Jun 2012 13:22:01 +0800, Jovi Zhang wrote: >> Hi guys, >> >> Does perf support user space hw_breakpoint based on per-task? >> >> perf already support kenerl space hw_breakpoint, but there don't have >> any example for >> user-space hw_breakpoint in code base(and never metion it). >> From perf api point of view, it should support per-task hw_breakpoint easily. >> but I still want to make sure that?(badly I don't have any linux >> machine to test it now:)) >> > > Here is my simple test: > > namhyung@sejong:perf$ nm -nD /usr/bin/ls | grep D > 0000000000619ce0 D quoting_style_args > 000000000061a530 D ls_mode > 000000000061a538 D Version > 000000000061a540 D argmatch_die > 000000000061a548 D exit_failure > > namhyung@sejong:perf$ ./perf stat -e mem:0x61a530 -e mem:0x61a538 -- /usr/bin/ls > /dev/null > > Performance counter stats for '/usr/bin/ls': > > 1 mem:0x61a530:rw > 0 mem:0x61a538:rw > > 0.002213595 seconds time elapsed > > > So, it should work on user-space hw_breakpoints.
Thanks very much, it works.
> > 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. > > Thanks, > Namhyung
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?
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 [unhandled content-type:application/octet-stream] | |