Re: [PATCH] Use more flexible pattern matching for CPU identification for mapfile.csv
From: Ravi Bangoria
Date: Thu Nov 23 2017 - 01:06:42 EST
Hi William,
On 11/23/2017 12:56 AM, Arnaldo Carvalho de Melo wrote:
Em Wed, Nov 22, 2017 at 11:08:49AM -0500, William Cohen escreveu:
The powerpc cpuid information includes chip revision information.
Changes between chip revisions are usually minor bug fixes and usually
do not affect the operation of the performance monitoring hardware.
The original mapfile.csv matching requires enumerating every possible
cpuid string. When a new minor chip revision is produced a new entry
has to be added to the mapfile.csv and the code recompiled to allow
perf to have the implementation specific perf events for this new
minor revision. For users of various distibutions of Linux having to
wait for a new release of the kernel's perf tool to be built with
these trivial patches is inconvenient.
Using regular expressions rather than exactly string matching of the
entire cpuid string allows developers to write mapfile.csv files that
do not require patches and recompiles for each of these minor version
changes. If special cases need to be made for some particular
versions, they can be placed earlier in the mapfile.csv file before
the more general matches.
This is a good idea. I think the patch can be optimized a bit.
Please see my comments.
Looks ok, but you forgot to add lkml to the CC list, I'm doing that now
and also adding Ravi Bangoria @ IBM, which sent yet another of those
lines that would match your regexp.
Ravi & IBM crew, please see if we can proceed with Will's regexp approach, ok?
- Arnaldo
Signed-off-by: William Cohen <wcohen@xxxxxxxxxx>
---
tools/perf/pmu-events/arch/powerpc/mapfile.csv | 14 +++------
tools/perf/pmu-events/arch/x86/mapfile.csv | 5 +---
tools/perf/pmu-events/jevents.c | 39 +++++++++++++++++++++++++-
tools/perf/util/pmu.c | 20 ++++++++++++-
4 files changed, 62 insertions(+), 16 deletions(-)
diff --git a/tools/perf/pmu-events/arch/powerpc/mapfile.csv b/tools/perf/pmu-events/arch/powerpc/mapfile.csv
index a0f3a11ca19f..9ad0469057b8 100644
--- a/tools/perf/pmu-events/arch/powerpc/mapfile.csv
+++ b/tools/perf/pmu-events/arch/powerpc/mapfile.csv
@@ -13,13 +13,7 @@
#
# Power8 entries
-004b0000,1,power8,core
-004b0201,1,power8,core
-004c0000,1,power8,core
-004d0000,1,power8,core
-004d0100,1,power8,core
-004d0200,1,power8,core
-004c0100,1,power8,core
-004e0100,1,power9,core
-004e0200,1,power9,core
-004e1200,1,power9,core
+004b[[:xdigit:]]\+,1,power8,core
+004c[[:xdigit:]]\+,1,power8,core
+004d[[:xdigit:]]\+,1,power8,core
+004e[[:xdigit:]]\+,1,power9,core
Instead of 3 regex for Power8, can we compact it into only 1:
004[bcd][[:xdigit:]]...
Both Power8 and Power9 revision number are 16 bits so,
instead of arbitrary number of xdigit, I think, we can limit
it to 4:ÂÂ [[:xdigit:]]{4}
AFAIK, you _have to_ use REG_EXTENDED in both regcomp()
and regexec() to make it work.
diff --git a/tools/perf/pmu-events/arch/x86/mapfile.csv b/tools/perf/pmu-events/arch/x86/mapfile.csv
index fe1a2c47cabf..93656f2fd53a 100644
--- a/tools/perf/pmu-events/arch/x86/mapfile.csv
+++ b/tools/perf/pmu-events/arch/x86/mapfile.csv
@@ -23,10 +23,7 @@ GenuineIntel-6-1E,v2,nehalemep,core
GenuineIntel-6-1F,v2,nehalemep,core
GenuineIntel-6-1A,v2,nehalemep,core
GenuineIntel-6-2E,v2,nehalemex,core
-GenuineIntel-6-4E,v24,skylake,core
-GenuineIntel-6-5E,v24,skylake,core
-GenuineIntel-6-8E,v24,skylake,core
-GenuineIntel-6-9E,v24,skylake,core
+GenuineIntel-6-[4589]E,v24,skylake,core
ÂOk, so all entries for powerpc are regex, but its not the case with x86?
GenuineIntel-6-37,v13,silvermont,core
GenuineIntel-6-4D,v13,silvermont,core
GenuineIntel-6-4C,v13,silvermont,core
diff --git a/tools/perf/pmu-events/jevents.c b/tools/perf/pmu-events/jevents.c
index 9eb7047bafe4..4102664ac1bf 100644
--- a/tools/perf/pmu-events/jevents.c
+++ b/tools/perf/pmu-events/jevents.c
@@ -116,6 +116,43 @@ static void fixdesc(char *s)
*e = 0;
}
+/* Add escapes for '\' so they are proper C strings. */
+static char *fixregex(char *s)
+{
+ int len = 0;
+ int esc_count = 0;
+ char *fixed = NULL;
+ char *p, *q;
+
+ /* Count the number of '\' in string */
+ for (p = s; *p; p++) {
+ ++len;
+ if (*p == '\\')
+ ++esc_count;
+ }
+
+ if (esc_count == 0)
+ return s;
+
+ /* allocate space for a new string */
+ fixed = (char *) malloc(len+1);
+ if (!fixed)
+ return NULL;
+
+ /* copy over the characters */
+ q = fixed;
+ for (p = s; *p; p++) {
+ if (*p == '\\') {
+ *q = '\\';
+ ++q;
+ }
+ *q = *p;
+ ++q;
+ }
+ *q = '\0';
+ return fixed;
+}
+
AFAICS, you are processing cpuid to add one more '\' if
you find '\' in regex. Can't you directly use '\\' in mapfile?
Something like:
004b[[:xdigit:]]\\+,1,power8,core
Then you don't need this function at all.
static struct msrmap {
const char *num;
const char *pname;
@@ -648,7 +685,7 @@ static int process_mapfile(FILE *outfp, char *fpath)
}
line[strlen(line)-1] = '\0';
- cpuid = strtok_r(p, ",", &save);
+ cpuid = fixregex(strtok_r(p, ",", &save));
version = strtok_r(NULL, ",", &save);
fname = strtok_r(NULL, ",", &save);
type = strtok_r(NULL, ",", &save);
diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 07cb2ac041d7..56942b748d87 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -12,6 +12,7 @@
#include <dirent.h>
#include <api/fs/fs.h>
#include <locale.h>
+#include <regex.h>
#include "util.h"
#include "pmu.h"
#include "parse-events.h"
@@ -570,14 +571,31 @@ struct pmu_events_map *perf_pmu__find_map(void)
i = 0;
for (;;) {
+ regex_t re;
+ regmatch_t pmatch[1];
+ int match;
+
map = &pmu_events_map[i++];
if (!map->table) {
map = NULL;
break;
}
- if (!strcmp(map->cpuid, cpuid))
+ if (regcomp(&re, map->cpuid, 0) != 0) {
+ /* Warn unable to generate match particular string. */
+ pr_info("Invalid regular expression %s\n", map->cpuid);
break;
+ }
+
+ match = !regexec(&re, cpuid, 1, pmatch, REG_EXTENDED);
+ regfree(&re);
+ if (match) {
+ size_t match_len = (pmatch[0].rm_eo - pmatch[0].rm_so);
+
+ /* Verify the entire string matched. */
I think, if you can add '$' at the end of regex, you don't need this
check.
So, f.e. for powerpc, final content of the file may look like:
004[bcd][[:xdigit:]]{4}$,1,power8,core
004e[[:xdigit:]]{4}$,1,power9,core
Though, I haven't gone through x86 entries. Please make sure
my comments works for all archs before changing the patch.
Thanks,
Ravi
+ if (match_len == strlen(cpuid))
+ break;
+ }
}
free(cpuid);
return map;
--
2.13.6