datastore vs. t.lock2

[Shawn Michael]

On our database servers we had some bad luck with ext3 in RedHat's default 
install.  The performance just wasn't anything like what we had hoped it 
would be.  The fix for us was to modify one of the mount options.

Try the following options to mount:

defaults,noatime,data=writeback

The data=writeback helped tremendously under heavy IO and the noatime helps 
to reduce needless IO.  How many people acutally need atime?

On 2003.01.30 17:31 Matthias Andree wrote:
> Hi,
> 
> I've seen t.lock2 take time in the range of minutes on an ext3fs file
> system (Linux), while I usually run tests on a reiserfs file system
> where it takes in the range of seconds. I conduct these tests on a
> Fujitsu MAH-3182MP U160 SCSI 7200/min drive. I straced the program and
> found it to call fsync() often next to the close(), and I heard the disk
> grind.
> 
> I'm asking myself two questions:
> 
> 1. might reiserfs cheat again or suffer from a broken fsync()
>    implementation or is it really so much faster than ext3fs for
>    synchronous operations? Something to test for somebody, but beyond
>    bogofilter's scope.
> 
> 2. Might this have killed the Debian MIPS little endian (mipsel) buildd
>    t.lock2? I can imagine that under I/O contention a slow drive, this
>    test takes ages. Interesting to look at for me.
> 
> I'll change the db_close to allow a "bool nosync" be passed in which is
> then used in wordlists_open when it defers execution because it cannot
> obtain a lock.
> 
> This change might cause bogofilter to be more easy on the hardware and
> to finish quicker by inferring less hardware-induced (mechanical)
> latency times. We'll see, I'll do some benchmarks.
> 
> --
> Matthias Andree
> 
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