From: Andi Kleen <andi@firstfloor.org>
To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>,
jolsa@redhat.com, linux-kernel@vger.kernel.org,
namhyung@kernel.org, Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH 02/10] perf, tools: Support handling complete branch stacks as histograms
Date: Thu, 13 Nov 2014 21:15:24 +0100 [thread overview]
Message-ID: <20141113201524.GU12538@two.firstfloor.org> (raw)
In-Reply-To: <20141113200833.GI3612@kernel.org>
On Thu, Nov 13, 2014 at 05:08:33PM -0300, Arnaldo Carvalho de Melo wrote:
> Em Thu, Nov 13, 2014 at 08:52:08PM +0100, Andi Kleen escreveu:
> > On Thu, Nov 13, 2014 at 04:14:17PM -0300, Arnaldo Carvalho de Melo wrote:
> > > Em Wed, Nov 12, 2014 at 06:05:20PM -0800, Andi Kleen escreveu:
> > > > +static int remove_loops(struct branch_entry *l, int nr)
> > > > +{
> > > > + int i, j, off;
> > > > + unsigned char chash[CHASHSZ];
> > > > +
> > > > + memset(chash, NO_ENTRY, sizeof(chash));
> > > > +
> > > > + BUG_ON(nr >= 256);
> > >
> > > What is wrong with return -1 and propagating the error, so that the user
> > > is informed if the data being processed is bogus, stop processing with a
> > > warning or continue processing if finding the next valid record is
> > > possible?
> >
> > The error doesn't depend on the record. There is a check for the record
> > being < 127 in front of this. This is merely to catch that
> > if someone increases PERF_MAX_BRANCH_DEPTH to below 255 they need
> > to increase the type of the hash table from u8.
>
> Ok, so this would be better as a BUILD_BUG_ON?
Yes that should work.
-Andi
>
> Like:
>
> #define CHASHSZ 127
> #define CHASHBITS 7
> #define NO_ENTRY 0xff
>
> #define PERF_MAX_BRANCH_DEPTH 127
>
> /* Remove loops. */
> static int remove_loops(struct branch_entry *l, int nr)
> {
> int i, j, off;
> unsigned char chash[CHASHSZ];
>
> memset(chash, NO_ENTRY, sizeof(chash));
>
> /* Change the type of the chash table, u8 is not enough now */
> BUILD_BUG_ON(PERF_MAX_BRANCH_DEPTH >= 256);
> for (i = 0; i < nr; i++) {
> int h = hash_64(l[i].from, CHASHBITS) % CHASHSZ;
>
> -------------------------------------
>
> - Arnaldo
>
--
ak@linux.intel.com -- Speaking for myself only.
next prev parent reply other threads:[~2014-11-13 20:15 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-13 2:05 Implement lbr-as-callgraph v10 Andi Kleen
2014-11-13 2:05 ` [PATCH 01/10] perf, tools: Factor out adding new call chain entries Andi Kleen
2014-11-13 19:14 ` Arnaldo Carvalho de Melo
2014-11-20 7:37 ` [tip:perf/core] perf callchain: " tip-bot for Andi Kleen
2014-11-13 2:05 ` [PATCH 02/10] perf, tools: Support handling complete branch stacks as histograms Andi Kleen
2014-11-13 19:14 ` Arnaldo Carvalho de Melo
2014-11-13 19:52 ` Andi Kleen
2014-11-13 20:08 ` Arnaldo Carvalho de Melo
2014-11-13 20:15 ` Andi Kleen [this message]
2014-11-13 20:42 ` Arnaldo Carvalho de Melo
2014-12-08 6:53 ` [tip:perf/core] perf callchain: " tip-bot for Andi Kleen
2014-11-13 2:05 ` [PATCH 03/10] perf, tools: Use al.addr to set up call chain Andi Kleen
2014-11-13 19:16 ` Arnaldo Carvalho de Melo
2014-12-11 21:46 ` Jiri Olsa
2014-12-11 22:27 ` Andi Kleen
2014-11-20 7:38 ` [tip:perf/core] perf callchain: " tip-bot for Andi Kleen
2014-11-13 2:05 ` [PATCH 04/10] perf, tools: Add --branch-history option to report Andi Kleen
2014-12-08 6:53 ` [tip:perf/core] perf report: Add --branch-history option tip-bot for Andi Kleen
2014-11-13 2:05 ` [PATCH 05/10] perf, tools: Use a common function to resolve symbol or name Andi Kleen
2014-11-13 19:17 ` Arnaldo Carvalho de Melo
2014-11-20 7:38 ` [tip:perf/core] perf callchain: " tip-bot for Andi Kleen
2014-11-13 2:05 ` [PATCH 06/10] perf, tools: Enable printing the srcline in the history Andi Kleen
2014-11-13 19:20 ` Arnaldo Carvalho de Melo
2014-12-08 6:48 ` [tip:perf/core] perf callchain: " tip-bot for Andi Kleen
2014-11-13 2:05 ` [PATCH 07/10] perf, tools: Only print base source file for srcline Andi Kleen
2014-11-13 19:22 ` Arnaldo Carvalho de Melo
2014-11-20 7:38 ` [tip:perf/core] perf " tip-bot for Andi Kleen
2014-11-13 2:05 ` [PATCH 08/10] perf, tools: Support source line numbers in annotate Andi Kleen
2014-11-13 20:52 ` Arnaldo Carvalho de Melo
2014-11-20 7:39 ` [tip:perf/core] perf annotate: " tip-bot for Andi Kleen
2014-11-13 2:05 ` [PATCH 09/10] tools, perf: Make get_srcline fall back to sym+offset Andi Kleen
2014-12-08 6:49 ` [tip:perf/core] perf callchain: " tip-bot for Andi Kleen
2014-11-13 2:05 ` [PATCH 10/10] tools, perf: Add asprintf replacement Andi Kleen
2014-11-13 20:53 ` Arnaldo Carvalho de Melo
2014-11-13 21:14 ` Andi Kleen
2014-11-17 21:34 ` Implement lbr-as-callgraph v10 Arnaldo Carvalho de Melo
2014-11-18 1:56 ` Andi Kleen
2014-11-18 10:44 ` Jiri Olsa
2014-11-18 11:00 ` Jiri Olsa
2014-11-18 13:37 ` Arnaldo Carvalho de Melo
2014-11-19 15:31 ` Andi Kleen
2014-11-19 6:21 ` Namhyung Kim
2014-11-19 9:23 ` Jiri Olsa
2014-11-19 10:54 ` Jiri Olsa
2014-11-19 14:10 ` Arnaldo Carvalho de Melo
2014-11-19 16:04 ` Arnaldo Carvalho de Melo
2014-11-19 21:48 ` Andi Kleen
2014-11-20 19:33 ` Arnaldo Carvalho de Melo
2014-11-20 20:46 ` Andi Kleen
2014-11-21 20:30 ` Arnaldo Carvalho de Melo
2014-11-22 1:25 ` Andi Kleen
2014-11-24 7:40 ` Namhyung Kim
2014-11-19 21:50 ` Andi Kleen
2014-11-20 20:36 ` Arnaldo Carvalho de Melo
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