Serious performance issues, broken initialization, and a likely fix

Ade Lovett ade at FreeBSD.org
Sun Aug 14 09:17:03 GMT 2005


Ade Lovett wrote:
> To cut a long story short, the order in which nswbuf is being
> initialized is completely, totally, and utterly wrong -- this was
> introduced by revision 1.132 of vm/vnode_pager.c just over 4 years ago.

This is now logged as kern/84903 and, as the PR states, IMO 6.0 should
*NOT* be released until a resolution is found to this problem.

The current misinitialization of nswbuf will affect *any* system where
there are even a reasonable number of attempted concurrent disk reads.

I'm certainly willing to work with someone to get a definitive patch
made, however we do *not* run HEAD here, only RELENG_6, so that will
have to be taken into consideration.

-aDe


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