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Re: [PATCH]: Increase size of FSFS dir cache

From: Greg Stein <gstein_at_lyra.org>
Date: 2005-11-07 02:43:08 CET

On Mon, Oct 31, 2005 at 12:45:48PM -0700, Garrett Rooney wrote:
> On 10/29/05, Daniel Berlin <dberlin@dberlin.org> wrote:
>
> > 1. Anybody who doesn't have enough memory to hold 128 dirs of their repo
> > in memory is probably in trouble anyway. Assuming 100k of info per dir,
> > that's only ..... 12.8 meg of memory, *if they hit all the dirs*, and
> > they had probably about 1000 files per dir (to generate 100k of info).
> > This seems reasonable to me.
>
> This seems like a reasonable tradeoff for the speed gain, although

Is it reasonable? Adding 12.8 meg in absolute terms isn't a big deal.
Now do it for 100 concurrent sessions.

Oops.

Individual connection footprints are just one piece of the puzzle.
They *still* have to stay tiny so that a given server can service more
than three clients.

I've seen CVS take several hundred meg. Hey, no problem. The server
had 4 gig of memory. Hah! It wasn't so fun as the server went into
swap death when a half-dozen people tried to update their client.

(and yes, I see this has been committed, but I still think there is
 concern around adding to the per-connection footprint like this)

Cheers,
-g

-- 
Greg Stein, http://www.lyra.org/
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Received on Mon Nov 7 02:40:54 2005

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