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Re: more cvs performance questions (I think they are at least

From: Larry Jones
Subject: Re: more cvs performance questions (I think they are at least
Date: Wed, 29 Oct 2003 00:16:19 -0500 (EST)

Mark D. Baushke writes [about locks on in-memory filesystems]:
> If you are able to write to memory faster than to your repository, then
> the difference in speed between those to mediums is how much faster you
> will be able to create your lock. I would guess that in most cases of
> a repository over NFS, or slow local disks the use of a memory filesystem
> would be faster. The use of a swap system that is always being paged out
> to disk may actually be slower if the page disk is slow.

Most filesystems have to worry about the on-disk filesystem being
consistent in the event of a system crash or power failure.  In many
cases, that means that operations that modify the filesystem metadata
(such as creating or deleting a file or directory) are synchronous --
the system actually waits for the data to get written to the disk before
continuing.  Memory filesystems aren't persistent, so they can avoid
that.  Since locking is just creating and deleting lots of little files
and directories, that can make a big difference, even if the memory
filesystem might get paged out to backing store eventually.

And anyone with a "slow" paging disk deserves what they get, the paging
disk should be the fastest disk in the system.

-Larry Jones

These findings suggest a logical course of action. -- Calvin

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