From: Arnaldo Carvalho de Melo <acme@redhat.com>
To: Stephane Eranian <eranian@google.com>
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
mingo@elte.hu, robert.richter@amd.com, ming.m.lin@intel.com,
andi@firstfloor.org, asharma@fb.com, ravitillo@lbl.gov,
vweaver1@eecs.utk.edu, khandual@linux.vnet.ibm.com,
dsahern@gmail.com
Subject: Re: [PATCH v5 16/18] perf: enable reading of perf.data files from different ABI rev
Date: Mon, 6 Feb 2012 16:22:08 -0200 [thread overview]
Message-ID: <20120206182208.GH6367@infradead.org> (raw)
In-Reply-To: <1328187288-24395-17-git-send-email-eranian@google.com>
Em Thu, Feb 02, 2012 at 01:54:46PM +0100, Stephane Eranian escreveu:
> This patch allows perf to process perf.data files generated
> using an ABI that has a different perf_event_attr struct size, i.e.,
> a different ABI version.
>
> The perf_event_attr can be extended, yet perf needs to cope with
> older perf.data files. Similarly, perf must be able to cope with
> a perf.data file which is using a newer version of the ABI than
> what it knows about.
>
> This patch adds read_attr(), a routine that reads a perf_event_attr
> struct from a file incrementally based on its advertised size. If
> the on-file struct is smaller than what perf knows, then the extra
> fields are zeroed. If the on-file struct is bigger, then perf only
> uses what it knows about, the rest is skipped.
Anshuman, can I have your Acked-by or Reviewed-by since you spotted
problems in this and your suggestions were taken into account? Is this
OK now?
- Arnaldo
> Signed-off-by: Stephane Eranian <eranian@google.com>
> ---
> tools/perf/util/header.c | 49 ++++++++++++++++++++++++++++++++++++++++++++-
> 1 files changed, 47 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
> index 6f4187d..8d6c18d 100644
> --- a/tools/perf/util/header.c
> +++ b/tools/perf/util/header.c
> @@ -1959,6 +1959,51 @@ static int perf_header__read_pipe(struct perf_session *session, int fd)
> return 0;
> }
>
> +static int read_attr(int fd, struct perf_header *ph,
> + struct perf_file_attr *f_attr)
> +{
> + struct perf_event_attr *attr = &f_attr->attr;
> + size_t sz, left;
> + size_t our_sz = sizeof(f_attr->attr);
> + int ret;
> +
> + memset(f_attr, 0, sizeof(*f_attr));
> +
> + /* read minimal guaranteed structure */
> + ret = readn(fd, attr, PERF_ATTR_SIZE_VER0);
> + if (ret <= 0)
> + return -1;
> +
> + /* on file perf_event_attr size */
> + sz = attr->size;
> + if (ph->needs_swap)
> + sz = bswap_32(sz);
> +
> + if (sz == 0) {
> + /* assume ABI0 */
> + sz = PERF_ATTR_SIZE_VER0;
> + } else if (sz > our_sz) {
> + /* bigger than what we know about */
> + sz = our_sz;
> +
> + /* skip what we do not know about */
> + lseek(fd, SEEK_CUR, attr->size - our_sz);
> + }
> + /* what we have not yet read and that we know about */
> + left = sz - PERF_ATTR_SIZE_VER0;
> + if (left) {
> + void *ptr = attr;
> + ptr += PERF_ATTR_SIZE_VER0;
> +
> + ret = readn(fd, ptr, left);
> + if (ret <= 0)
> + return -1;
> + }
> + /* read the ids */
> + ret = readn(fd, &f_attr->ids, sizeof(struct perf_file_section));
> + return ret <= 0 ? -1 : 0;
> +}
> +
> int perf_session__read_header(struct perf_session *session, int fd)
> {
> struct perf_header *header = &session->header;
> @@ -1979,14 +2024,14 @@ int perf_session__read_header(struct perf_session *session, int fd)
> return -EINVAL;
> }
>
> - nr_attrs = f_header.attrs.size / sizeof(f_attr);
> + nr_attrs = f_header.attrs.size / f_header.attr_size;
> lseek(fd, f_header.attrs.offset, SEEK_SET);
>
> for (i = 0; i < nr_attrs; i++) {
> struct perf_evsel *evsel;
> off_t tmp;
>
> - if (readn(fd, &f_attr, sizeof(f_attr)) <= 0)
> + if (read_attr(fd, header, &f_attr) < 0)
> goto out_errno;
>
> if (header->needs_swap)
> --
> 1.7.4.1
next prev parent reply other threads:[~2012-02-06 18:52 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-02 12:54 [PATCH v5 00/18] perf: add support for sampling taken branches Stephane Eranian
2012-02-02 12:54 ` [PATCH v5 01/18] perf: add generic taken branch sampling support Stephane Eranian
2012-02-02 12:54 ` [PATCH v5 02/18] perf: add Intel LBR MSR definitions Stephane Eranian
2012-02-02 12:54 ` [PATCH v5 03/18] perf: add Intel X86 LBR sharing logic Stephane Eranian
2012-02-02 12:54 ` [PATCH v5 04/18] perf: sync branch stack sampling with X86 precise_sampling Stephane Eranian
2012-02-02 12:54 ` [PATCH v5 05/18] perf: add Intel X86 LBR mappings for PERF_SAMPLE_BRANCH filters Stephane Eranian
2012-02-02 12:54 ` [PATCH v5 06/18] perf: disable LBR support for older Intel Atom processors Stephane Eranian
2012-02-02 12:54 ` [PATCH v5 07/18] perf: implement PERF_SAMPLE_BRANCH for Intel X86 Stephane Eranian
2012-02-02 12:54 ` [PATCH v5 08/18] perf: add LBR software filter support " Stephane Eranian
2012-02-02 12:54 ` [PATCH v5 09/18] perf: disable PERF_SAMPLE_BRANCH_* when not supported Stephane Eranian
2012-02-06 19:23 ` Peter Zijlstra
2012-02-06 19:59 ` Stephane Eranian
2012-02-02 12:54 ` [PATCH v5 10/18] perf: add hook to flush branch_stack on context switch Stephane Eranian
2012-02-02 12:54 ` [PATCH v5 11/18] perf: add code to support PERF_SAMPLE_BRANCH_STACK Stephane Eranian
2012-02-06 18:06 ` Arnaldo Carvalho de Melo
2012-02-07 14:11 ` Stephane Eranian
2012-02-07 15:21 ` Arnaldo Carvalho de Melo
2012-02-02 12:54 ` [PATCH v5 12/18] perf: add support for sampling taken branch to perf record Stephane Eranian
2012-02-06 18:08 ` Arnaldo Carvalho de Melo
2012-02-02 12:54 ` [PATCH v5 13/18] perf: add support for taken branch sampling to perf report Stephane Eranian
2012-02-06 18:14 ` Arnaldo Carvalho de Melo
2012-02-02 12:54 ` [PATCH v5 14/18] perf: fix endianness detection in perf.data Stephane Eranian
2012-02-06 18:17 ` Arnaldo Carvalho de Melo
2012-02-06 18:18 ` Stephane Eranian
2012-02-06 21:47 ` David Ahern
2012-02-06 22:06 ` Arnaldo Carvalho de Melo
2012-02-06 22:29 ` David Ahern
2012-02-07 14:13 ` Stephane Eranian
2012-02-07 14:38 ` Arnaldo Carvalho de Melo
2012-02-17 9:42 ` [tip:perf/core] perf tools: " tip-bot for Stephane Eranian
2012-02-02 12:54 ` [PATCH v5 15/18] perf: add ABI reference sizes Stephane Eranian
2012-02-02 12:54 ` [PATCH v5 16/18] perf: enable reading of perf.data files from different ABI rev Stephane Eranian
2012-02-06 18:19 ` Arnaldo Carvalho de Melo
2012-02-06 18:22 ` Arnaldo Carvalho de Melo [this message]
2012-02-07 7:03 ` Anshuman Khandual
2012-02-07 14:52 ` Arnaldo Carvalho de Melo
2012-02-06 22:19 ` David Ahern
2012-02-07 15:50 ` Stephane Eranian
2012-02-07 16:41 ` David Ahern
2012-02-07 17:42 ` Stephane Eranian
2012-02-07 17:57 ` David Ahern
2012-02-02 12:54 ` [PATCH v5 17/18] perf: fix bug print_event_desc() Stephane Eranian
2012-02-02 12:54 ` [PATCH v5 18/18] perf: make perf able to read file from older ABIs Stephane Eranian
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