Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754047Ab0LLUQZ (ORCPT ); Sun, 12 Dec 2010 15:16:25 -0500 Received: from mail-bw0-f45.google.com ([209.85.214.45]:38424 "EHLO mail-bw0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753950Ab0LLUQX (ORCPT ); Sun, 12 Dec 2010 15:16:23 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=V6HrnskNJiVzqssFQsYWWqbBmYK0LakoqhHdMSUg0/3h+rxkeQFyWhdWXGcvrddDqb x+Wz4InNOi82Z4AHy54NEiihFcO1ER10AE/Z7Dd98olfYnsv56YEBhuEzgHzN8usFS2N HpNbd9fBTBDnLUL9/RDwUdCwSPYY1VMeRVqQw= Date: Sun, 12 Dec 2010 21:16:16 +0100 From: Frederic Weisbecker To: David Ahern Cc: linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] perf tools: Add reference timestamp to perf header Message-ID: <20101212201613.GA1784@nowhere> References: <1291773285-16254-1-git-send-email-daahern@cisco.com> <1291773285-16254-2-git-send-email-daahern@cisco.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1291773285-16254-2-git-send-email-daahern@cisco.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5585 Lines: 172 On Tue, Dec 07, 2010 at 06:54:44PM -0700, David Ahern wrote: > Add a reference timestamp to the perf header - snapshotting kernel > time to gettimeofday. This allows 'perf report' to convert kernel > timestamps to time-of-day which is convenient for comparing to other > (non perf related) log files. > > The timestamp is added using a feature bit for compatibility with > older binaries and data files. > > Signed-off-by: David Ahern > --- > tools/perf/util/header.c | 51 +++++++++++++++++++++++++++++++++++++++++++++ > tools/perf/util/header.h | 3 ++ > tools/perf/util/session.c | 26 +++++++++++++++++++++++ > 3 files changed, 80 insertions(+), 0 deletions(-) > > diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c > index 76e949a..2fe893b 100644 > --- a/tools/perf/util/header.c > +++ b/tools/perf/util/header.c > @@ -191,6 +191,40 @@ static int write_padded(int fd, const void *bf, size_t count, > return err; > } > > +static int perf_header__read_ref_time(struct perf_header *header, > + int fd, u64 offset, u64 size) > +{ > + size_t sz_nsec = sizeof(header->nsec_ref); > + size_t sz_tv = sizeof(header->tv_ref); > + int err = -1; > + > + if (((size - offset) < (sz_nsec + sz_tv)) || > + (read(fd, &header->nsec_ref, sz_nsec) != (ssize_t) sz_nsec) || > + (read(fd, &header->tv_ref, sz_tv) != (ssize_t) sz_tv)) > + goto out; Hmm, could we have endianness related troubles if we write the timespec on an arch and cross read from another, or other cross read issues? > + > + err = 0; > + > +out: > + return err; > +} > + > +static int perf_header__write_ref_time(struct perf_header *header, int fd) > +{ > + size_t sz_nsec = sizeof(header->nsec_ref); > + size_t sz_tv = sizeof(header->tv_ref); > + int err = -1; > + > + if ((write(fd, &header->nsec_ref, sz_nsec) != (ssize_t) sz_nsec) || > + (write(fd, &header->tv_ref, sz_tv) != (ssize_t) sz_tv)) > + goto out; > + > + err = 0; > + > +out: > + return err; > +} > + > #define dsos__for_each_with_build_id(pos, head) \ > list_for_each_entry(pos, head, node) \ > if (!pos->has_build_id) \ > @@ -483,6 +517,19 @@ static int perf_header__adds_write(struct perf_header *self, int fd) > perf_session__cache_build_ids(session); > } > > + if (perf_header__has_feat(self, HEADER_REFERENCE_TIME)) { > + struct perf_file_section *tref_sec; > + > + tref_sec = &feat_sec[idx++]; > + tref_sec->offset = lseek(fd, 0, SEEK_CUR); > + err = perf_header__write_ref_time(self, fd); > + if (err < 0) { > + pr_debug("failed to write reference time\n"); > + goto out_free; > + } > + tref_sec->size = lseek(fd, 0, SEEK_CUR) - tref_sec->offset; > + } > + > lseek(fd, sec_start, SEEK_SET); > err = do_write(fd, feat_sec, sec_size); > if (err < 0) > @@ -810,6 +857,10 @@ static int perf_file_section__process(struct perf_file_section *self, > if (perf_header__read_build_ids(ph, fd, self->offset, self->size)) > pr_debug("Failed to read buildids, continuing...\n"); > break; > + case HEADER_REFERENCE_TIME: > + if (perf_header__read_ref_time(ph, fd, self->offset, self->size)) > + pr_debug("Failed to read reference time, continuing...\n"); > + break; > default: > pr_debug("unknown feature %d, continuing...\n", feat); > } > diff --git a/tools/perf/util/header.h b/tools/perf/util/header.h > index 6335965..0721c78 100644 > --- a/tools/perf/util/header.h > +++ b/tools/perf/util/header.h > @@ -19,6 +19,7 @@ struct perf_header_attr { > enum { > HEADER_TRACE_INFO = 1, > HEADER_BUILD_ID, > + HEADER_REFERENCE_TIME, > HEADER_LAST_FEATURE, > }; > > @@ -59,6 +60,8 @@ struct perf_header { > u64 data_size; > u64 event_offset; > u64 event_size; > + u64 nsec_ref; > + struct timeval tv_ref; > DECLARE_BITMAP(adds_features, HEADER_FEAT_BITS); > }; > > diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c > index 3074d38..720838e 100644 > --- a/tools/perf/util/session.c > +++ b/tools/perf/util/session.c > @@ -110,6 +110,29 @@ void perf_session__update_sample_type(struct perf_session *self) > perf_session__id_header_size(self); > } > > +static int perf_session__create_ref_time(struct perf_session *session) > +{ > + struct timespec tp; > + > + /* race here between successive calls, but should be close enough */ > + if (gettimeofday(&session->header.tv_ref, NULL) != 0) { > + pr_err("gettimeofday failed. Cannot set reference time.\n"); > + return -1; > + } > + > + if (clock_gettime(CLOCK_MONOTONIC, &tp) != 0) { > + pr_err("clock_gettime failed. Cannot set reference time.\n"); > + return -1; > + } > + > + session->header.nsec_ref = (u64) tp.tv_sec * NSEC_PER_SEC > + + (u64) tp.tv_nsec; > + > + perf_header__set_feat(&session->header, HEADER_REFERENCE_TIME); > + > + return 0; > +} > + > int perf_session__create_kernel_maps(struct perf_session *self) > { > int ret = machine__create_kernel_maps(&self->host_machine); > @@ -167,6 +190,9 @@ struct perf_session *perf_session__new(const char *filename, int mode, bool forc > */ > if (perf_session__create_kernel_maps(self) < 0) > goto out_delete; > + > + if (perf_session__create_ref_time(self) < 0) > + goto out_delete; So, it does record it anytime? > } > > perf_session__update_sample_type(self); Other than that, looks good! -- 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/