From: | Andres Freund <andres(at)2ndquadrant(dot)com> |
---|---|
To: | pgsql-committers(at)postgresql(dot)org |
Cc: | Robert Haas <rhaas(at)postgresql(dot)org> |
Subject: | Re: pgsql: Dramatically reduce System V shared memory consumption. |
Date: | 2012-06-29 17:34:05 |
Message-ID: | 201206291934.05319.andres@2ndquadrant.com |
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Lists: | pgsql-committers |
Hi Robert,
You have a small typo in the patch:
+ /*
+ * pagesize will, for practical purposes, always be a power of two.
+ * But just in case it isn't, we do it this way instead of using
+ * TYPEALIGN().
+ */
+ AnonymousShmemSize = size;
+ if (size % pagesize != 0)
+ AnonymousShmemSize += pagesize - (size % pagesize);
+
+ /*
+ * We assume that no one will attempt to run PostgreSQL 9.3 or later
+ * on systems that are ancient enough that anonymous shared memory is
+ * not supported, such as pre-2.4 versions of Linux. If that turns
out
+ * to be false, we might need to add a run-time test here and do this
+ * only if the running kernel supports it.
+ */
+ AnonymousShmem = mmap(NULL, size, PROT_READ|PROT_WRITE, PG_MMAP_FLAGS,
+ -1, 0);
Note that you use size in the mmap...
Andres
--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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