Date: Sat, 1 Jul 2023 15:49:36 +0800
From: Julien Rouhaud <rjuju123@gmail.com>
To: pgsql-hackers@lists.postgresql.org
Subject: Outdated description of PG_CACHE_LINE_SIZE
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Hi,

I just noticed that the comment for PG_CACHE_LINE_SIZE still says that "it's
currently used in xlog.c", which hasn't been true for quite some time.

PFA a naive patch to make the description more generic.

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From a554ee9ca3558c1cc67b2f4024c13b26aacff3c9 Mon Sep 17 00:00:00 2001
From: Julien Rouhaud <julien.rouhaud@free.fr>
Date: Sat, 1 Jul 2023 15:41:54 +0800
Subject: [PATCH v1] Fix PG_CACHE_LINE_SIZE description.

PG_CACHE_LINE_SIZE was originally only used in xlog.c, but this hasn't been
true for a very long time and is now wildly used, so modify its description to
not mention any explicit source code file.

Author: Julien Rouhaud
Reviewed-by: FIXME
Discussion: FIXME
---
 src/include/pg_config_manual.h | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/src/include/pg_config_manual.h b/src/include/pg_config_manual.h
index a1a93ad706..01fe2af499 100644
--- a/src/include/pg_config_manual.h
+++ b/src/include/pg_config_manual.h
@@ -218,12 +218,11 @@
 
 /*
  * Assumed cache line size. This doesn't affect correctness, but can be used
- * for low-level optimizations. Currently, this is used to pad some data
- * structures in xlog.c, to ensure that highly-contended fields are on
- * different cache lines. Too small a value can hurt performance due to false
- * sharing, while the only downside of too large a value is a few bytes of
- * wasted memory. The default is 128, which should be large enough for all
- * supported platforms.
+ * for low-level optimizations. This is mostly used to pad various data
+ * structures, to ensure that highly-contended fields are on different cache
+ * lines. Too small a value can hurt performance due to false sharing, while
+ * the only downside of too large a value is a few bytes of wasted memory. The
+ * default is 128, which should be large enough for all supported platforms.
  */
 #define PG_CACHE_LINE_SIZE		128
 
-- 
2.37.0


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