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SubjectRe: cache limit
On Tue, Sep 02, 2003 at 07:52:51PM +0900, Takao Indoh wrote:
> According to this information, many I/O increase pagecache and cause
> memory shortage.
> fadvise may be effective, but fadvise always releases cache
> even if there are enough free memory, and may degrade performance.
> In the case of /proc tunable,
> pagecache is not released until system memory become lack.
[...]
> If so, limiting pagecache seems to be effective for DBMS.

There are reasons why databases use raw io and direct io; this is one
of them. I'd say the kernel shouldn't try to engage in such tunable
shenanigans.


-- wli
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On Tue, Sep 02, 2003 at 07:52:51PM +0900, Takao Indoh wrote:
> According to this information, many I/O increase pagecache and cause
> memory shortage.
> fadvise may be effective, but fadvise always releases cache
> even if there are enough free memory, and may degrade performance.
> In the case of /proc tunable,
> pagecache is not released until system memory become lack.
[...]
> If so, limiting pagecache seems to be effective for DBMS.

There are reasons why databases use raw io and direct io; this is one
of them. I'd say the kernel shouldn't try to engage in such tunable
shenanigans.


-- wli
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

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