Re: Remove the limit on the number of entries allowed in catcaches, - Mailing list pgsql-hackers

From Qingqing Zhou
Subject Re: Remove the limit on the number of entries allowed in catcaches,
Date
Msg-id e6rahf$g0i$1@news.hub.org
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In response to Re: Remove the limit on the number of entries allowed in catcaches,  (Simon Riggs <simon@2ndquadrant.com>)
Responses Re: Remove the limit on the number of entries allowed in  (Simon Riggs <simon@2ndquadrant.com>)
List pgsql-hackers
"Simon Riggs" <simon@2ndquadrant.com> wrote
>
> Can we do the same for the file descriptors in fd.c?
>
> Very often the total number of file descriptors is much less than the
> maximum, so it would make sense to only maintain the LRU when we are
> using more than 50%-75% of the maximum.
>

I am not against doing it but AFAIR the LRU file operations is (1) not
frequent; (2) the cost is only several CPU circles if we do not run out of
fds; (3) the LRU lseek/close/open big cost is still not avoidable when we
really run out of fds. So this optimization may be not needed. Or do you
have some numbers to show that's a bottleneck for some kind of applications?

Regards,
Qingqing




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