Date: Fri, 24 Jan 2014 20:07:05 -0500 From: J David <j.david.lists@gmail.com> To: Rick Macklem <rmacklem@uoguelph.ca> Cc: freebsd-net@freebsd.org Subject: Re: Terrible NFS performance under 9.2-RELEASE? Message-ID: <CABXB=RSGhshBe3CWDiQcis4fYYHqRbyQr70QiXM1nLMTSyCQvQ@mail.gmail.com> In-Reply-To: <179007387.16041087.1390608600325.JavaMail.root@uoguelph.ca> References: <CABXB=RTTCfxP_Ebp3aa4k9qr5QrGDVQQMr1R1w0wBTUBD1OtwA@mail.gmail.com> <179007387.16041087.1390608600325.JavaMail.root@uoguelph.ca>
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On Fri, Jan 24, 2014 at 7:10 PM, Rick Macklem <rmacklem@uoguelph.ca> wrote:
> I would like to hear if you find Linux doing read before write when
> you use "-r 2k", since I think that is writing less than a page.
It doesn't. As I reported in the original test, I used an 8k
rsize/wsize and a 4k write size on the Linux test and no
read-before-write was observed. And just now I did as you asked, a 2k
test with Linux mounting with 32k rsize/wsize. No extra reads,
excellent performance. FreeBSD, with the same mount options, does
reads even on the appends in this case and can't.
random random
KB reclen write rewrite read reread read write
Linux 1048576 2 281082 358672 125687 121964
FreeBSD 1048576 2 59042 22624 10304
1933
For comparison, here's the same test with 32k reclen (again, both
Linux and FreeBSD using 32k rsize/wsize):
random random
KB reclen write rewrite read reread read write
Linux 1048576 32 319387 373021 411106 364393
FreeBSD 1048576 32 74892 73703 34889 66350
Unfortunately it sounds like this state of affairs isn't really going
to improve, at least in the near future. If there was one area where
I never thought Linux would surpass us, it was NFS. :(
Thanks!
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