Em Fri, Jun 07, 2019 at 02:44:25PM +0800, Leo Yan escreveu:
> On Thu, Jun 06, 2019 at 05:10:56PM -0300, Arnaldo Carvalho de Melo wrote:
> > Em Wed, Jun 05, 2019 at 10:16:33AM -0600, Mathieu Poirier escreveu:
> > > This patch adds the necessay intelligence to properly compute the value
> > > of 'old' and 'head' when operating in snapshot mode. That way we can get
> > > the latest information in the AUX buffer and be compatible with the
> > > generic AUX ring buffer mechanic.
> >
> > Leo, have you had the chance to test/review this one? Suzuki?
>
> Sure. I applied this patch on the perf/core branch (with latest
> commit 3e4fbf36c1e3 'perf augmented_raw_syscalls: Move reading
> filename to the loop') and passed testing with below steps:
>
> # perf record -e cs_etm/@tmc_etr0/ -S -m,64 --per-thread ./sort &
> [1] 19097
> Bubble sorting array of 30000 elements
>
> # kill -USR2 19097
> # kill -USR2 19097
> # kill -USR2 19097
> [ perf record: Woken up 4 times to write data ]
> [ perf record: Captured and wrote 0.753 MB perf.data ]
>
> FWIW:
>
> Tested-by: Leo Yan <leo....@linaro.org>
Thanks a lot, I've added your "Tester notes:" and also your Tested-by:.
As I don't have hardware (yet) to test these patches, tests by people
who can test on real hardware is always super appreciated.
Any suggestions for a SBC that I could buy to be able to do so?
Regards,
- Arnaldo
> > I also changed the subject to:
> >
> > [PATCH] perf cs-etm: Properly set the value of 'old' and 'head' in
> > snapshot mode
> >
> > So that when looking at a 'git log --oneline' one can have the proper
> > context and know that its about cs-etm.
> >
> > - Arnaldo
> >
> > > Signed-off-by: Mathieu Poirier <mathieu.poir...@linaro.org>
> > > ---
> > > tools/perf/arch/arm/util/cs-etm.c | 127 +++++++++++++++++++++++++++++-
> > > 1 file changed, 123 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/tools/perf/arch/arm/util/cs-etm.c
> > > b/tools/perf/arch/arm/util/cs-etm.c
> > > index 911426721170..0a278bbcaba6 100644
> > > --- a/tools/perf/arch/arm/util/cs-etm.c
> > > +++ b/tools/perf/arch/arm/util/cs-etm.c
> > > @@ -31,6 +31,8 @@ struct cs_etm_recording {
> > > struct auxtrace_record itr;
> > > struct perf_pmu *cs_etm_pmu;
> > > struct perf_evlist *evlist;
> > > + int wrapped_cnt;
> > > + bool *wrapped;
> > > bool snapshot_mode;
> > > size_t snapshot_size;
> > > };
> > > @@ -536,16 +538,131 @@ static int cs_etm_info_fill(struct auxtrace_record
> > > *itr,
> > > return 0;
> > > }
> > >
> > > -static int cs_etm_find_snapshot(struct auxtrace_record *itr
> > > __maybe_unused,
> > > +static int cs_etm_alloc_wrapped_array(struct cs_etm_recording *ptr, int
> > > idx)
> > > +{
> > > + bool *wrapped;
> > > + int cnt = ptr->wrapped_cnt;
> > > +
> > > + /* Make @ptr->wrapped as big as @idx */
> > > + while (cnt <= idx)
> > > + cnt++;
> > > +
> > > + /*
> > > + * Free'ed in cs_etm_recording_free(). Using realloc() to avoid
> > > + * cross compilation problems where the host's system supports
> > > + * reallocarray() but not the target.
> > > + */
> > > + wrapped = realloc(ptr->wrapped, cnt * sizeof(bool));
> > > + if (!wrapped)
> > > + return -ENOMEM;
> > > +
> > > + wrapped[cnt - 1] = false;
> > > + ptr->wrapped_cnt = cnt;
> > > + ptr->wrapped = wrapped;
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +static bool cs_etm_buffer_has_wrapped(unsigned char *buffer,
> > > + size_t buffer_size, u64 head)
> > > +{
> > > + u64 i, watermark;
> > > + u64 *buf = (u64 *)buffer;
> > > + size_t buf_size = buffer_size;
> > > +
> > > + /*
> > > + * We want to look the very last 512 byte (chosen arbitrarily) in
> > > + * the ring buffer.
> > > + */
> > > + watermark = buf_size - 512;
> > > +
> > > + /*
> > > + * @head is continuously increasing - if its value is equal or greater
> > > + * than the size of the ring buffer, it has wrapped around.
> > > + */
> > > + if (head >= buffer_size)
> > > + return true;
> > > +
> > > + /*
> > > + * The value of @head is somewhere within the size of the ring buffer.
> > > + * This can be that there hasn't been enough data to fill the ring
> > > + * buffer yet or the trace time was so long that @head has numerically
> > > + * wrapped around. To find we need to check if we have data at the very
> > > + * end of the ring buffer. We can reliably do this because mmap'ed
> > > + * pages are zeroed out and there is a fresh mapping with every new
> > > + * session.
> > > + */
> > > +
> > > + /* @head is less than 512 byte from the end of the ring buffer */
> > > + if (head > watermark)
> > > + watermark = head;
> > > +
> > > + /*
> > > + * Speed things up by using 64 bit transactions (see "u64 *buf" above)
> > > + */
> > > + watermark >>= 3;
> > > + buf_size >>= 3;
> > > +
> > > + /*
> > > + * If we find trace data at the end of the ring buffer, @head has
> > > + * been there and has numerically wrapped around at least once.
> > > + */
> > > + for (i = watermark; i < buf_size; i++)
> > > + if (buf[i])
> > > + return true;
> > > +
> > > + return false;
> > > +}
> > > +
> > > +static int cs_etm_find_snapshot(struct auxtrace_record *itr,
> > > int idx, struct auxtrace_mmap *mm,
> > > - unsigned char *data __maybe_unused,
> > > + unsigned char *data,
> > > u64 *head, u64 *old)
> > > {
> > > + int err;
> > > + bool wrapped;
> > > + struct cs_etm_recording *ptr =
> > > + container_of(itr, struct cs_etm_recording, itr);
> > > +
> > > + /*
> > > + * Allocate memory to keep track of wrapping if this is the first
> > > + * time we deal with this *mm.
> > > + */
> > > + if (idx >= ptr->wrapped_cnt) {
> > > + err = cs_etm_alloc_wrapped_array(ptr, idx);
> > > + if (err)
> > > + return err;
> > > + }
> > > +
> > > + /*
> > > + * Check to see if *head has wrapped around. If it hasn't only the
> > > + * amount of data between *head and *old is snapshot'ed to avoid
> > > + * bloating the perf.data file with zeros. But as soon as *head has
> > > + * wrapped around the entire size of the AUX ring buffer it taken.
> > > + */
> > > + wrapped = ptr->wrapped[idx];
> > > + if (!wrapped && cs_etm_buffer_has_wrapped(data, mm->len, *head)) {
> > > + wrapped = true;
> > > + ptr->wrapped[idx] = true;
> > > + }
> > > +
> > > pr_debug3("%s: mmap index %d old head %zu new head %zu size %zu\n",
> > > __func__, idx, (size_t)*old, (size_t)*head, mm->len);
> > >
> > > - *old = *head;
> > > - *head += mm->len;
> > > + /* No wrap has occurred, we can just use *head and *old. */
> > > + if (!wrapped)
> > > + return 0;
> > > +
> > > + /*
> > > + * *head has wrapped around - adjust *head and *old to pickup the
> > > + * entire content of the AUX buffer.
> > > + */
> > > + if (*head >= mm->len) {
> > > + *old = *head - mm->len;
> > > + } else {
> > > + *head += mm->len;
> > > + *old = *head - mm->len;
> > > + }
> > >
> > > return 0;
> > > }
> > > @@ -586,6 +703,8 @@ static void cs_etm_recording_free(struct
> > > auxtrace_record *itr)
> > > {
> > > struct cs_etm_recording *ptr =
> > > container_of(itr, struct cs_etm_recording, itr);
> > > +
> > > + zfree(&ptr->wrapped);
> > > free(ptr);
> > > }
> > >
> > > --
> > > 2.17.1
> >
> > --
> >
> > - Arnaldo
--
- Arnaldo
