[squid-users] Re: Re: Squid high bandwidth IO issue (ramdisk SSD)

On 02.08.2009, Adrian Chadd wrote:

> > 2. Format /dev/sdb1 with "mkfs.xfs -f -l lazy-count=1,version=2 -i attr=2 -d agcount=4"
> > 3. Mount it afterwards using "rw,noatime,logbsize=256k,logbufs=2,nobarrier" in fstab.
 
> > 4. Use cfq as the standard scheduler with the linux kernel
 
> Just out of curiousity, why these settings? Do you have any research
> which shows this?

I'll see what survived of all the testings I did. Had a harddisk crash in
the meantime and I'm not shure if I have saved the results. These are the parameters
related to XFS which gave the best latency and highest throughput on my
system with an OCZ SSD (cacheless). I "benchmarked" also ext2/3/4 and jfs,
and did it separately for cfq, dl, anticipatory and the noop elevator.

I had also posted some of these results on the lkml, here's one link
I found by a quick search, which shows how cfq outperforms dl nearly by a
factor of 10:

http://lkml.org/lkml/2009/4/8/664

I did a

 while : ; do time sh -c "dd if=/dev/zero of=bigfile bs=8M count=256 ; sync; rm bigfile"; done

to put the system under heavy I/O, and measured the responses with the
fsync-tester. The results were noticeable, also without measuring. I did
also a lot of bonnie++ runs:

 bonnie++ -u htd:users -d /mnt/test -s 16016m -m liesel -n 16:100000:16:64

> > (Btw: on my systems, squid-2.7 is noticeably _a lot_ slower than squid-3,
> > if the object is not in cache...)
 
> This is an interesting statement. I can't think of any specific reason
> why there should be any particular reason squid-2.7 performs worse
> than Squid-3 in this instance.

Forget about that. Yes, that's "black magic", and it's NOT a general statement,
but an observation. Was just interested in how squid-2 performs on an old P4
realted to squid-3. It's quite possible that I did something wrong which
was the cause.
Received on Sun Aug 02 2009 - 11:20:48 MDT