[PATCH v2 0/3] perf record: adapt NUMA awareness to machines with #CPUs > 1K

[PATCH v2 0/3] perf record: adapt NUMA awareness to machines with #CPUs > 1K

[Alexey Budankov]

Current implementation of cpu_set_t type by glibc has internal cpu
mask size limitation of no more than 1024 CPUs. This limitation confines
NUMA awareness of Perf tool in record mode, thru --affinity option,
to the first 1024 CPUs on machines with larger amount of CPUs.

This patch set enables Perf tool to overcome 1024 CPUs limitation by
using a dedicated struct mmap_cpu_mask type and applying tool's bitmap
API operations to manipulate affinity masks of the tool's thread and
the mmaped data buffers.

tools bitmap API has been extended with bitmap_free() function and
bitmap_equal() operation whose implementation is derived from the
kernel one.

---
Alexey Budankov (3):
  tools bitmap: implement bitmap_equal() operation at bitmap API
  perf mmap: declare type for cpu mask of arbitrary length
  perf record: adapt affinity to machines with #CPUs > 1K

 tools/include/linux/bitmap.h | 30 ++++++++++++++++++++++++++++++
 tools/lib/bitmap.c           | 15 +++++++++++++++
 tools/perf/builtin-record.c  | 30 ++++++++++++++++++++++++------
 tools/perf/util/mmap.c       | 31 +++++++++++++++++++++++++------
 tools/perf/util/mmap.h       | 11 ++++++++++-
 5 files changed, 104 insertions(+), 13 deletions(-)

---
Changes in v2:
- implemented bitmap_free() for symmetry with bitmap_alloc()
- capitalized MMAP_CPU_MASK_BYTES() macro
- returned -1 from perf_mmap__setup_affinity_mask()
- implemented releasing of masks using bitmap_free()
- moved debug printing under -vv option

---
Testing:

  tools/perf/perf record -vv --affinity=cpu -- ls
  thread mask[8]: empty
  Using CPUID GenuineIntel-6-5E-3
  intel_pt default config: tsc,mtc,mtc_period=3,psb_period=3,pt,branch
  nr_cblocks: 0
  affinity: CPU
  mmap flush: 1
  comp level: 0
  ------------------------------------------------------------
  perf_event_attr:
    size                             112
    { sample_period, sample_freq }   4000
    sample_type                      IP|TID|TIME|PERIOD
    read_format                      ID
    disabled                         1
    inherit                          1
    mmap                             1
    comm                             1
    freq                             1
    enable_on_exec                   1
    task                             1
    precise_ip                       3
    sample_id_all                    1
    exclude_guest                    1
    mmap2                            1
    comm_exec                        1
    ksymbol                          1
    bpf_event                        1
  ------------------------------------------------------------
  sys_perf_event_open: pid 28649  cpu 0  group_fd -1  flags 0x8 = 4
  sys_perf_event_open: pid 28649  cpu 1  group_fd -1  flags 0x8 = 5
  sys_perf_event_open: pid 28649  cpu 2  group_fd -1  flags 0x8 = 6
  sys_perf_event_open: pid 28649  cpu 3  group_fd -1  flags 0x8 = 9
  sys_perf_event_open: pid 28649  cpu 4  group_fd -1  flags 0x8 = 10
  sys_perf_event_open: pid 28649  cpu 5  group_fd -1  flags 0x8 = 11
  sys_perf_event_open: pid 28649  cpu 6  group_fd -1  flags 0x8 = 12
  sys_perf_event_open: pid 28649  cpu 7  group_fd -1  flags 0x8 = 13
  mmap size 528384B
  0x7f1898200010: mmap mask[8]: 0
  0x7f18982100d8: mmap mask[8]: 1
  0x7f18982201a0: mmap mask[8]: 2
  0x7f1898230268: mmap mask[8]: 3
  0x7f1898240330: mmap mask[8]: 4
  0x7f18982503f8: mmap mask[8]: 5
  0x7f18982604c0: mmap mask[8]: 6
  0x7f1898270588: mmap mask[8]: 7
  ------------------------------------------------------------
  perf_event_attr:
    type                             1
    size                             112
    config                           0x9
    watermark                        1
    sample_id_all                    1
    bpf_event                        1
    { wakeup_events, wakeup_watermark } 1
  ------------------------------------------------------------
  sys_perf_event_open: pid -1  cpu 0  group_fd -1  flags 0x8 = 14
  sys_perf_event_open: pid -1  cpu 1  group_fd -1  flags 0x8 = 15
  sys_perf_event_open: pid -1  cpu 2  group_fd -1  flags 0x8 = 16
  sys_perf_event_open: pid -1  cpu 3  group_fd -1  flags 0x8 = 17
  sys_perf_event_open: pid -1  cpu 4  group_fd -1  flags 0x8 = 18
  sys_perf_event_open: pid -1  cpu 5  group_fd -1  flags 0x8 = 19
  sys_perf_event_open: pid -1  cpu 6  group_fd -1  flags 0x8 = 20
  sys_perf_event_open: pid -1  cpu 7  group_fd -1  flags 0x8 = 21
  ...
  Synthesizing TSC conversion information
  thread mask[8]: 0
  thread mask[8]: 1
  thread mask[8]: 2
  thread mask[8]: 3
  thread mask[8]: 4
  arch			      copy     Documentation  init     kernel	 MAINTAINERS	  modules.builtin.modinfo  perf.data	  scripts   System.map	vmlinux
  block			      COPYING  drivers	      ipc      lbuild	 Makefile	  modules.order		   perf.data.old  security  tools	vmlinux.o
  certs			      CREDITS  fs	      Kbuild   lib	 mm		  Module.symvers	   README	  sound     usr
  config-5.2.7-100.fc29.x86_64  crypto   include	      Kconfig  LICENSES  modules.builtin  net			   samples	  stdio     virt
  thread mask[8]: 5
  thread mask[8]: 6
  thread mask[8]: 7
  thread mask[8]: 0
  thread mask[8]: 1
  thread mask[8]: 2
  thread mask[8]: 3
  thread mask[8]: 4
  thread mask[8]: 5
  thread mask[8]: 6
  thread mask[8]: 7
  [ perf record: Woken up 0 times to write data ]
  thread mask[8]: 0
  thread mask[8]: 1
  thread mask[8]: 2
  thread mask[8]: 3
  thread mask[8]: 4
  thread mask[8]: 5
  thread mask[8]: 6
  thread mask[8]: 7
  Looking at the vmlinux_path (8 entries long)
  Using vmlinux for symbols
  [ perf record: Captured and wrote 0.014 MB perf.data (8 samples) ]

-- 
2.20.1

[PATCH v2 1/3] tools bitmap: implement bitmap_equal() operation at bitmap API

[Alexey Budankov]

Extend tools bitmap API with bitmap_equal() implementation.
The implementation has been derived from the kernel.

Extend tools bitmap API with bitmap_free() implementation for
symmetry with bitmap_alloc() function.

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
Changes in v2:
- implemented bitmap_free() for symmetry with bitmap_alloc()

---
 tools/include/linux/bitmap.h | 30 ++++++++++++++++++++++++++++++
 tools/lib/bitmap.c           | 15 +++++++++++++++
 2 files changed, 45 insertions(+)

diff --git a/tools/include/linux/bitmap.h b/tools/include/linux/bitmap.h
index 05dca5c203f3..477a1cae513f 100644
--- a/tools/include/linux/bitmap.h
+++ b/tools/include/linux/bitmap.h
@@ -15,6 +15,8 @@ void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
 		 const unsigned long *bitmap2, int bits);
 int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
 		 const unsigned long *bitmap2, unsigned int bits);
+int __bitmap_equal(const unsigned long *bitmap1,
+		   const unsigned long *bitmap2, unsigned int bits);
 void bitmap_clear(unsigned long *map, unsigned int start, int len);
 
 #define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 1)))
@@ -123,6 +125,15 @@ static inline unsigned long *bitmap_alloc(int nbits)
 	return calloc(1, BITS_TO_LONGS(nbits) * sizeof(unsigned long));
 }
 
+/*
+ * bitmap_free - Free bitmap
+ * @bitmap: pointer to bitmap
+ */
+static inline void bitmap_free(unsigned long *bitmap)
+{
+	free(bitmap);
+}
+
 /*
  * bitmap_scnprintf - print bitmap list into buffer
  * @bitmap: bitmap
@@ -148,4 +159,23 @@ static inline int bitmap_and(unsigned long *dst, const unsigned long *src1,
 	return __bitmap_and(dst, src1, src2, nbits);
 }
 
+#ifdef __LITTLE_ENDIAN
+#define BITMAP_MEM_ALIGNMENT 8
+#else
+#define BITMAP_MEM_ALIGNMENT (8 * sizeof(unsigned long))
+#endif
+#define BITMAP_MEM_MASK (BITMAP_MEM_ALIGNMENT - 1)
+#define IS_ALIGNED(x, a) (((x) & ((typeof(x))(a) - 1)) == 0)
+
+static inline int bitmap_equal(const unsigned long *src1,
+			const unsigned long *src2, unsigned int nbits)
+{
+	if (small_const_nbits(nbits))
+		return !((*src1 ^ *src2) & BITMAP_LAST_WORD_MASK(nbits));
+	if (__builtin_constant_p(nbits & BITMAP_MEM_MASK) &&
+	    IS_ALIGNED(nbits, BITMAP_MEM_ALIGNMENT))
+		return !memcmp(src1, src2, nbits / 8);
+	return __bitmap_equal(src1, src2, nbits);
+}
+
 #endif /* _PERF_BITOPS_H */
diff --git a/tools/lib/bitmap.c b/tools/lib/bitmap.c
index 38494782be06..5043747ef6c5 100644
--- a/tools/lib/bitmap.c
+++ b/tools/lib/bitmap.c
@@ -71,3 +71,18 @@ int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
 			   BITMAP_LAST_WORD_MASK(bits));
 	return result != 0;
 }
+
+int __bitmap_equal(const unsigned long *bitmap1,
+		const unsigned long *bitmap2, unsigned int bits)
+{
+	unsigned int k, lim = bits/BITS_PER_LONG;
+	for (k = 0; k < lim; ++k)
+		if (bitmap1[k] != bitmap2[k])
+			return 0;
+
+	if (bits % BITS_PER_LONG)
+		if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
+			return 0;
+
+	return 1;
+}
-- 
2.20.1

[PATCH v2 2/3] perf mmap: declare type for cpu mask of arbitrary length

[Alexey Budankov]

Declare a dedicated struct map_cpu_mask type for cpu masks of
arbitrary length. Mask is available thru bits pointer and the
mask length is kept in nbits field. MMAP_CPU_MASK_BYTES() macro
returns mask storage size in bytes.

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
Changes in v2:
- capitalized MMAP_CPU_MASK_BYTES() macro

---
 tools/perf/util/mmap.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/tools/perf/util/mmap.h b/tools/perf/util/mmap.h
index bee4e83f7109..786c235d6062 100644
--- a/tools/perf/util/mmap.h
+++ b/tools/perf/util/mmap.h
@@ -15,6 +15,15 @@
 #include "event.h"
 
 struct aiocb;
+
+struct mmap_cpu_mask {
+	unsigned long *bits;
+	size_t nbits;
+};
+
+#define MMAP_CPU_MASK_BYTES(m) \
+	(BITS_TO_LONGS(((struct mmap_cpu_mask *)m)->nbits) * sizeof(unsigned long))
+
 /**
  * struct mmap - perf's ring buffer mmap details
  *
-- 
2.20.1

[PATCH v2 3/3] perf record: adapt affinity to machines with #CPUs > 1K

[Alexey Budankov]

Use struct mmap_cpu_mask type for tool's thread and mmap data
buffers to overcome current 1024 CPUs mask size limitation of
cpu_set_t type.

Currently glibc cpu_set_t type has internal mask size limit
of 1024 CPUs. Moving to struct mmap_cpu_mask type allows
overcoming that limit. tools bitmap API is used to manipulate
objects of struct mmap_cpu_mask type.

Reported-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
Changes in v2:
- returned -1 from perf_mmap__setup_affinity_mask()
- moved debug printing under -vv option
- implemented releasing of masks using bitmap_free()

---
 tools/perf/builtin-record.c | 30 ++++++++++++++++++++++++------
 tools/perf/util/mmap.c      | 31 +++++++++++++++++++++++++------
 tools/perf/util/mmap.h      |  2 +-
 3 files changed, 50 insertions(+), 13 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index b95c000c1ed9..f38d9de8183f 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -62,6 +62,7 @@
 #include <linux/string.h>
 #include <linux/time64.h>
 #include <linux/zalloc.h>
+#include <linux/bitmap.h>
 
 struct switch_output {
 	bool		 enabled;
@@ -93,7 +94,7 @@ struct record {
 	bool			timestamp_boundary;
 	struct switch_output	switch_output;
 	unsigned long long	samples;
-	cpu_set_t		affinity_mask;
+	struct mmap_cpu_mask	affinity_mask;
 	unsigned long		output_max_size;	/* = 0: unlimited */
 };
 
@@ -951,13 +952,21 @@ static struct perf_event_header finished_round_event = {
 	.type = PERF_RECORD_FINISHED_ROUND,
 };
 
+#define MASK_SIZE 1023
 static void record__adjust_affinity(struct record *rec, struct mmap *map)
 {
+	char mask[MASK_SIZE + 1] = {0};
+
 	if (rec->opts.affinity != PERF_AFFINITY_SYS &&
-	    !CPU_EQUAL(&rec->affinity_mask, &map->affinity_mask)) {
-		CPU_ZERO(&rec->affinity_mask);
-		CPU_OR(&rec->affinity_mask, &rec->affinity_mask, &map->affinity_mask);
-		sched_setaffinity(0, sizeof(rec->affinity_mask), &rec->affinity_mask);
+	    !bitmap_equal(rec->affinity_mask.bits, map->affinity_mask.bits,
+			  rec->affinity_mask.nbits)) {
+		bitmap_zero(rec->affinity_mask.bits, rec->affinity_mask.nbits);
+		bitmap_or(rec->affinity_mask.bits, rec->affinity_mask.bits,
+			  map->affinity_mask.bits, rec->affinity_mask.nbits);
+		sched_setaffinity(0, MMAP_CPU_MASK_BYTES(&rec->affinity_mask),
+				  (cpu_set_t *)rec->affinity_mask.bits);
+		bitmap_scnprintf(rec->affinity_mask.bits, rec->affinity_mask.nbits, mask, MASK_SIZE);
+		pr_debug2("thread mask[%ld]: %s\n", rec->affinity_mask.nbits, mask);
 	}
 }
 
@@ -2389,7 +2398,6 @@ int cmd_record(int argc, const char **argv)
 # undef REASON
 #endif
 
-	CPU_ZERO(&rec->affinity_mask);
 	rec->opts.affinity = PERF_AFFINITY_SYS;
 
 	rec->evlist = evlist__new();
@@ -2455,6 +2463,14 @@ int cmd_record(int argc, const char **argv)
 
 	symbol__init(NULL);
 
+	rec->affinity_mask.nbits = cpu__max_cpu();
+	rec->affinity_mask.bits = bitmap_alloc(rec->affinity_mask.nbits);
+	if (!rec->affinity_mask.bits) {
+		pr_err("Failed to allocate thread mask for %ld cpus\n", rec->affinity_mask.nbits);
+		return -ENOMEM;
+	}
+	pr_debug2("thread mask[%ld]: empty\n", rec->affinity_mask.nbits);
+
 	err = record__auxtrace_init(rec);
 	if (err)
 		goto out;
@@ -2569,6 +2585,8 @@ int cmd_record(int argc, const char **argv)
 
 	err = __cmd_record(&record, argc, argv);
 out:
+	if (rec->affinity_mask.bits)
+		bitmap_free(rec->affinity_mask.bits);
 	evlist__delete(rec->evlist);
 	symbol__exit();
 	auxtrace_record__free(rec->itr);
diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
index 063d1b93c53d..3b097ae7f5fd 100644
--- a/tools/perf/util/mmap.c
+++ b/tools/perf/util/mmap.c
@@ -23,6 +23,7 @@
 #include "mmap.h"
 #include "../perf.h"
 #include <internal/lib.h> /* page_size */
+#include <linux/bitmap.h>
 
 size_t mmap__mmap_len(struct mmap *map)
 {
@@ -207,6 +208,9 @@ static void perf_mmap__aio_munmap(struct mmap *map __maybe_unused)
 
 void mmap__munmap(struct mmap *map)
 {
+	if (map->affinity_mask.bits)
+		bitmap_free(map->affinity_mask.bits);
+
 	perf_mmap__aio_munmap(map);
 	if (map->data != NULL) {
 		munmap(map->data, mmap__mmap_len(map));
@@ -215,7 +219,7 @@ void mmap__munmap(struct mmap *map)
 	auxtrace_mmap__munmap(&map->auxtrace_mmap);
 }
 
-static void build_node_mask(int node, cpu_set_t *mask)
+static void build_node_mask(int node, struct mmap_cpu_mask *mask)
 {
 	int c, cpu, nr_cpus;
 	const struct perf_cpu_map *cpu_map = NULL;
@@ -228,28 +232,43 @@ static void build_node_mask(int node, cpu_set_t *mask)
 	for (c = 0; c < nr_cpus; c++) {
 		cpu = cpu_map->map[c]; /* map c index to online cpu index */
 		if (cpu__get_node(cpu) == node)
-			CPU_SET(cpu, mask);
+			set_bit(cpu, mask->bits);
 	}
 }
 
-static void perf_mmap__setup_affinity_mask(struct mmap *map, struct mmap_params *mp)
+static int perf_mmap__setup_affinity_mask(struct mmap *map, struct mmap_params *mp)
 {
-	CPU_ZERO(&map->affinity_mask);
+	map->affinity_mask.nbits = cpu__max_cpu();
+	map->affinity_mask.bits = bitmap_alloc(map->affinity_mask.nbits);
+	if (!map->affinity_mask.bits)
+		return -1;
+
 	if (mp->affinity == PERF_AFFINITY_NODE && cpu__max_node() > 1)
 		build_node_mask(cpu__get_node(map->core.cpu), &map->affinity_mask);
 	else if (mp->affinity == PERF_AFFINITY_CPU)
-		CPU_SET(map->core.cpu, &map->affinity_mask);
+		set_bit(map->core.cpu, map->affinity_mask.bits);
+
+	return 0;
 }
 
+#define MASK_SIZE 1023
 int mmap__mmap(struct mmap *map, struct mmap_params *mp, int fd, int cpu)
 {
+	char mask[MASK_SIZE + 1] = {0};
+
 	if (perf_mmap__mmap(&map->core, &mp->core, fd, cpu)) {
 		pr_debug2("failed to mmap perf event ring buffer, error %d\n",
 			  errno);
 		return -1;
 	}
 
-	perf_mmap__setup_affinity_mask(map, mp);
+	if (perf_mmap__setup_affinity_mask(map, mp)) {
+		pr_debug2("failed to alloc mmap affinity mask, error %d\n",
+			  errno);
+		return -1;
+	}
+	bitmap_scnprintf(map->affinity_mask.bits, map->affinity_mask.nbits, mask, MASK_SIZE);
+	pr_debug2("%p: mmap mask[%ld]: %s\n", map, map->affinity_mask.nbits, mask);
 
 	map->core.flush = mp->flush;
 
diff --git a/tools/perf/util/mmap.h b/tools/perf/util/mmap.h
index 786c235d6062..65f9b04c45e4 100644
--- a/tools/perf/util/mmap.h
+++ b/tools/perf/util/mmap.h
@@ -40,7 +40,7 @@ struct mmap {
 		int		 nr_cblocks;
 	} aio;
 #endif
-	cpu_set_t	affinity_mask;
+	struct mmap_cpu_mask	affinity_mask;
 	void		*data;
 	int		comp_level;
 };
-- 
2.20.1

Re: [PATCH v2 3/3] perf record: adapt affinity to machines with #CPUs > 1K

[Jiri Olsa]

On Mon, Nov 25, 2019 at 09:08:57AM +0300, Alexey Budankov wrote:

SNIP

> -static void perf_mmap__setup_affinity_mask(struct mmap *map, struct mmap_params *mp)
> +static int perf_mmap__setup_affinity_mask(struct mmap *map, struct mmap_params *mp)
>  {
> -	CPU_ZERO(&map->affinity_mask);
> +	map->affinity_mask.nbits = cpu__max_cpu();
> +	map->affinity_mask.bits = bitmap_alloc(map->affinity_mask.nbits);
> +	if (!map->affinity_mask.bits)
> +		return -1;
> +
>  	if (mp->affinity == PERF_AFFINITY_NODE && cpu__max_node() > 1)
>  		build_node_mask(cpu__get_node(map->core.cpu), &map->affinity_mask);
>  	else if (mp->affinity == PERF_AFFINITY_CPU)
> -		CPU_SET(map->core.cpu, &map->affinity_mask);
> +		set_bit(map->core.cpu, map->affinity_mask.bits);
> +
> +	return 0;
>  }
>  
> +#define MASK_SIZE 1023
>  int mmap__mmap(struct mmap *map, struct mmap_params *mp, int fd, int cpu)
>  {
> +	char mask[MASK_SIZE + 1] = {0};

does this need to be initialized?

> +
>  	if (perf_mmap__mmap(&map->core, &mp->core, fd, cpu)) {
>  		pr_debug2("failed to mmap perf event ring buffer, error %d\n",
>  			  errno);
>  		return -1;
>  	}
>  
> -	perf_mmap__setup_affinity_mask(map, mp);
> +	if (perf_mmap__setup_affinity_mask(map, mp)) {
> +		pr_debug2("failed to alloc mmap affinity mask, error %d\n",
> +			  errno);
> +		return -1;
> +	}
> +	bitmap_scnprintf(map->affinity_mask.bits, map->affinity_mask.nbits, mask, MASK_SIZE);
> +	pr_debug2("%p: mmap mask[%ld]: %s\n", map, map->affinity_mask.nbits, mask);

the bitmap_scnprintf could be called only for debug case, right?

	if (version >= 2) {
		bitmap_scnprintf(map->affinity_mask.bits, map->affinity_mask.nbits, mask, MASK_SIZE);
		pr_debug2("%p: mmap mask[%ld]: %s\n", map, map->affinity_mask.nbits, mask);
	}

ditto int the record__adjust_affinity function

jirka

Re: [PATCH v2 3/3] perf record: adapt affinity to machines with #CPUs > 1K

[Alexey Budankov]

On 25.11.2019 12:42, Jiri Olsa wrote:
> On Mon, Nov 25, 2019 at 09:08:57AM +0300, Alexey Budankov wrote:
> 
> SNIP
> 
>> -static void perf_mmap__setup_affinity_mask(struct mmap *map, struct mmap_params *mp)
>> +static int perf_mmap__setup_affinity_mask(struct mmap *map, struct mmap_params *mp)
>>  {
>> -	CPU_ZERO(&map->affinity_mask);
>> +	map->affinity_mask.nbits = cpu__max_cpu();
>> +	map->affinity_mask.bits = bitmap_alloc(map->affinity_mask.nbits);
>> +	if (!map->affinity_mask.bits)
>> +		return -1;
>> +
>>  	if (mp->affinity == PERF_AFFINITY_NODE && cpu__max_node() > 1)
>>  		build_node_mask(cpu__get_node(map->core.cpu), &map->affinity_mask);
>>  	else if (mp->affinity == PERF_AFFINITY_CPU)
>> -		CPU_SET(map->core.cpu, &map->affinity_mask);
>> +		set_bit(map->core.cpu, map->affinity_mask.bits);
>> +
>> +	return 0;
>>  }
>>  
>> +#define MASK_SIZE 1023
>>  int mmap__mmap(struct mmap *map, struct mmap_params *mp, int fd, int cpu)
>>  {
>> +	char mask[MASK_SIZE + 1] = {0};
> 
> does this need to be initialized?

This is to make sure the message is zero terminated for vfprintf call()

> 
>> +
>>  	if (perf_mmap__mmap(&map->core, &mp->core, fd, cpu)) {
>>  		pr_debug2("failed to mmap perf event ring buffer, error %d\n",
>>  			  errno);
>>  		return -1;
>>  	}
>>  
>> -	perf_mmap__setup_affinity_mask(map, mp);
>> +	if (perf_mmap__setup_affinity_mask(map, mp)) {
>> +		pr_debug2("failed to alloc mmap affinity mask, error %d\n",
>> +			  errno);
>> +		return -1;
>> +	}
>> +	bitmap_scnprintf(map->affinity_mask.bits, map->affinity_mask.nbits, mask, MASK_SIZE);
>> +	pr_debug2("%p: mmap mask[%ld]: %s\n", map, map->affinity_mask.nbits, mask);
> 
> the bitmap_scnprintf could be called only for debug case, right?

Right. It is required to prepare debug message.

> 
> 	if (version >= 2) {
> 		bitmap_scnprintf(map->affinity_mask.bits, map->affinity_mask.nbits, mask, MASK_SIZE);
> 		pr_debug2("%p: mmap mask[%ld]: %s\n", map, map->affinity_mask.nbits, mask);
> 	}
> 
> ditto int the record__adjust_affinity function
> 
> jirka
> 
> 

~Alexey

Re: [PATCH v2 3/3] perf record: adapt affinity to machines with #CPUs > 1K

[Jiri Olsa]

On Mon, Nov 25, 2019 at 02:13:20PM +0300, Alexey Budankov wrote:
> On 25.11.2019 12:42, Jiri Olsa wrote:
> > On Mon, Nov 25, 2019 at 09:08:57AM +0300, Alexey Budankov wrote:
> > 
> > SNIP
> > 
> >> -static void perf_mmap__setup_affinity_mask(struct mmap *map, struct mmap_params *mp)
> >> +static int perf_mmap__setup_affinity_mask(struct mmap *map, struct mmap_params *mp)
> >>  {
> >> -	CPU_ZERO(&map->affinity_mask);
> >> +	map->affinity_mask.nbits = cpu__max_cpu();
> >> +	map->affinity_mask.bits = bitmap_alloc(map->affinity_mask.nbits);
> >> +	if (!map->affinity_mask.bits)
> >> +		return -1;
> >> +
> >>  	if (mp->affinity == PERF_AFFINITY_NODE && cpu__max_node() > 1)
> >>  		build_node_mask(cpu__get_node(map->core.cpu), &map->affinity_mask);
> >>  	else if (mp->affinity == PERF_AFFINITY_CPU)
> >> -		CPU_SET(map->core.cpu, &map->affinity_mask);
> >> +		set_bit(map->core.cpu, map->affinity_mask.bits);
> >> +
> >> +	return 0;
> >>  }
> >>  
> >> +#define MASK_SIZE 1023
> >>  int mmap__mmap(struct mmap *map, struct mmap_params *mp, int fd, int cpu)
> >>  {
> >> +	char mask[MASK_SIZE + 1] = {0};
> > 
> > does this need to be initialized?
> 
> This is to make sure the message is zero terminated for vfprintf call()

hum AFAICS it's used only in bitmap_scnprintf, which should
terminate the string properly

jirka

> 
> > 
> >> +
> >>  	if (perf_mmap__mmap(&map->core, &mp->core, fd, cpu)) {
> >>  		pr_debug2("failed to mmap perf event ring buffer, error %d\n",
> >>  			  errno);
> >>  		return -1;
> >>  	}
> >>  
> >> -	perf_mmap__setup_affinity_mask(map, mp);
> >> +	if (perf_mmap__setup_affinity_mask(map, mp)) {
> >> +		pr_debug2("failed to alloc mmap affinity mask, error %d\n",
> >> +			  errno);
> >> +		return -1;
> >> +	}
> >> +	bitmap_scnprintf(map->affinity_mask.bits, map->affinity_mask.nbits, mask, MASK_SIZE);
> >> +	pr_debug2("%p: mmap mask[%ld]: %s\n", map, map->affinity_mask.nbits, mask);
> > 
> > the bitmap_scnprintf could be called only for debug case, right?
> 
> Right. It is required to prepare debug message.
> 
> > 
> > 	if (version >= 2) {
> > 		bitmap_scnprintf(map->affinity_mask.bits, map->affinity_mask.nbits, mask, MASK_SIZE);
> > 		pr_debug2("%p: mmap mask[%ld]: %s\n", map, map->affinity_mask.nbits, mask);
> > 	}
> > 
> > ditto int the record__adjust_affinity function
> > 
> > jirka
> > 
> > 
> 
> ~Alexey
> 

Re: [PATCH v2 3/3] perf record: adapt affinity to machines with #CPUs > 1K

[Alexey Budankov]

On 25.11.2019 14:21, Jiri Olsa wrote:
> On Mon, Nov 25, 2019 at 02:13:20PM +0300, Alexey Budankov wrote:
>> On 25.11.2019 12:42, Jiri Olsa wrote:
>>> On Mon, Nov 25, 2019 at 09:08:57AM +0300, Alexey Budankov wrote:
>>>
>>> SNIP
>>>
>>>> -static void perf_mmap__setup_affinity_mask(struct mmap *map, struct mmap_params *mp)
>>>> +static int perf_mmap__setup_affinity_mask(struct mmap *map, struct mmap_params *mp)
>>>>  {
>>>> -	CPU_ZERO(&map->affinity_mask);
>>>> +	map->affinity_mask.nbits = cpu__max_cpu();
>>>> +	map->affinity_mask.bits = bitmap_alloc(map->affinity_mask.nbits);
>>>> +	if (!map->affinity_mask.bits)
>>>> +		return -1;
>>>> +
>>>>  	if (mp->affinity == PERF_AFFINITY_NODE && cpu__max_node() > 1)
>>>>  		build_node_mask(cpu__get_node(map->core.cpu), &map->affinity_mask);
>>>>  	else if (mp->affinity == PERF_AFFINITY_CPU)
>>>> -		CPU_SET(map->core.cpu, &map->affinity_mask);
>>>> +		set_bit(map->core.cpu, map->affinity_mask.bits);
>>>> +
>>>> +	return 0;
>>>>  }
>>>>  
>>>> +#define MASK_SIZE 1023
>>>>  int mmap__mmap(struct mmap *map, struct mmap_params *mp, int fd, int cpu)
>>>>  {
>>>> +	char mask[MASK_SIZE + 1] = {0};
>>>
>>> does this need to be initialized?
>>
>> This is to make sure the message is zero terminated for vfprintf call()
> 
> hum AFAICS it's used only in bitmap_scnprintf, which should
> terminate the string properly

If vfprintf() explicitly terminates output buffer with zero then
the initialization above can be avoided.

> 
> jirka
> 

~Alexey

Re: [PATCH v2 3/3] perf record: adapt affinity to machines with #CPUs > 1K

[Alexey Budankov]

On 25.11.2019 14:27, Alexey Budankov wrote:
> 
> On 25.11.2019 14:21, Jiri Olsa wrote:
>> On Mon, Nov 25, 2019 at 02:13:20PM +0300, Alexey Budankov wrote:
>>> On 25.11.2019 12:42, Jiri Olsa wrote:
>>>> On Mon, Nov 25, 2019 at 09:08:57AM +0300, Alexey Budankov wrote:
>>>>
>>>> SNIP
>>>>
>>>>> -static void perf_mmap__setup_affinity_mask(struct mmap *map, struct mmap_params *mp)
>>>>> +static int perf_mmap__setup_affinity_mask(struct mmap *map, struct mmap_params *mp)
>>>>>  {
>>>>> -	CPU_ZERO(&map->affinity_mask);
>>>>> +	map->affinity_mask.nbits = cpu__max_cpu();
>>>>> +	map->affinity_mask.bits = bitmap_alloc(map->affinity_mask.nbits);
>>>>> +	if (!map->affinity_mask.bits)
>>>>> +		return -1;
>>>>> +
>>>>>  	if (mp->affinity == PERF_AFFINITY_NODE && cpu__max_node() > 1)
>>>>>  		build_node_mask(cpu__get_node(map->core.cpu), &map->affinity_mask);
>>>>>  	else if (mp->affinity == PERF_AFFINITY_CPU)
>>>>> -		CPU_SET(map->core.cpu, &map->affinity_mask);
>>>>> +		set_bit(map->core.cpu, map->affinity_mask.bits);
>>>>> +
>>>>> +	return 0;
>>>>>  }
>>>>>  
>>>>> +#define MASK_SIZE 1023
>>>>>  int mmap__mmap(struct mmap *map, struct mmap_params *mp, int fd, int cpu)
>>>>>  {
>>>>> +	char mask[MASK_SIZE + 1] = {0};
>>>>
>>>> does this need to be initialized?
>>>
>>> This is to make sure the message is zero terminated for vfprintf call()
>>
>> hum AFAICS it's used only in bitmap_scnprintf, which should
>> terminate the string properly
> 
> If vfprintf() explicitly terminates output buffer with zero then
> the initialization above can be avoided.

Well, bitmap_scnprintf() returns the length of resulting string and 
the length can be used to make zero termination in the buffer and 
avoid mask initialization in the beginning.

~Alexey
 
> 
>>
>> jirka
>>
> 
> ~Alexey
>