linux-kernel - [PATCH 14/25] perf map: Use bitmap for booleans

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Message-Id: <20191119113245.19593-15-acme@kernel.org>
Date:   Tue, 19 Nov 2019 08:32:34 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
        Clark Williams <williams@...hat.com>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Andi Kleen <ak@...ux.intel.com>
Subject: [PATCH 14/25] perf map: Use bitmap for booleans

From: Arnaldo Carvalho de Melo <acme@...hat.com>

The map->priv and map->erange_warned are seldom used, the first only in
tests/vmlinux-kallsyms.c, the later only when hist_entry__inc_addr_samples()
returns -ERANGE in 'perf top', which are really rare occasions, so make
them a bool bitfield.

This will open up space for other members on the first cacheline.

  $ pahole -C map ~/bin/perf
  struct map {
  	union {
  		struct rb_node rb_node __attribute__((__aligned__(8))); /*     0    24 */
  		struct list_head node;                   /*     0    16 */
  	} __attribute__((__aligned__(8)));                                               /*     0    24 */
  	u64                        start;                /*    24     8 */
  	u64                        end;                  /*    32     8 */
  	_Bool                      erange_warned:1;      /*    40: 0  1 */
  	_Bool                      priv:1;               /*    40: 1  1 */

  	/* XXX 6 bits hole, try to pack */
  	/* XXX 3 bytes hole, try to pack */

  	u32                        prot;                 /*    44     4 */
  	u32                        flags;                /*    48     4 */

  	/* XXX 4 bytes hole, try to pack */

  	u64                        pgoff;                /*    56     8 */
  	/* --- cacheline 1 boundary (64 bytes) --- */
  	u64                        reloc;                /*    64     8 */
  	u32                        maj;                  /*    72     4 */
  	u32                        min;                  /*    76     4 */
  	u64                        ino;                  /*    80     8 */
  	u64                        ino_generation;       /*    88     8 */
  	u64                        (*map_ip)(struct map *, u64); /*    96     8 */
  	u64                        (*unmap_ip)(struct map *, u64); /*   104     8 */
  	struct dso *               dso;                  /*   112     8 */
  	refcount_t                 refcnt;               /*   120     4 */

  	/* size: 128, cachelines: 2, members: 17 */
  	/* sum members: 116, holes: 2, sum holes: 7 */
  	/* sum bitfield members: 2 bits, bit holes: 1, sum bit holes: 6 bits */
  	/* padding: 4 */
  	/* forced alignments: 1 */
  } __attribute__((__aligned__(8)));
  $

Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: Andi Kleen <ak@...ux.intel.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Namhyung Kim <namhyung@...nel.org>
Link: https://lkml.kernel.org/n/tip-g5545pcq4ff0wr17tfb1piqt@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/util/map.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/map.h b/tools/perf/util/map.h
index a31e80991189..e2466aa5bb41 100644
--- a/tools/perf/util/map.h
+++ b/tools/perf/util/map.h
@@ -25,8 +25,8 @@ struct map {
 	};
 	u64			start;
 	u64			end;
-	bool			erange_warned;
-	u32			priv;
+	bool			erange_warned:1;
+	bool			priv:1;
 	u32			prot;
 	u32			flags;
 	u64			pgoff;
-- 
2.21.0