Date: Tue, 24 Jun 2014 16:14:05 -0400 From: Mike Tancsa <mike@sentex.net> To: Rick Macklem <rmacklem@uoguelph.ca> Cc: FreeBSD-STABLE Mailing List <freebsd-stable@freebsd.org> Subject: Re: nfs slowdown (RELENG_8) Message-ID: <53A9DC0D.2000705@sentex.net> In-Reply-To: <53A987AE.8060708@sentex.net> References: <2091718059.2982836.1403563319620.JavaMail.root@uoguelph.ca> <53A978D1.2000207@sentex.net> <53A987AE.8060708@sentex.net>
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On 6/24/2014 10:14 AM, Mike Tancsa wrote: > > I also just tried with an igb nic and the same issue. These are i386 > boxes. I wonder if its something to do with that. (non PAE kernel) > OK, its not related to i386 as I found another box with em nics, i386 that works at full speed. One more strange issue I discovered is that there is a difference between dd and cat on the problem boxes. Normally, this would be uninteresting to me other than the fact that it seems the same underlying issue is impacting the performance of dump over NFS. e.g. on the two problem client problem boxes, if I do a simple test like # dd if=/dev/zero of=/nfsbackup/test count=200000 bs=1024 200000+0 records in 200000+0 records out 204800000 bytes transferred in 1.767594 secs (115863704 bytes/sec) which is close to gigabit speeds-- all is good. and if I do # cat /dev/zero | dd of=/nfsbackup/test count=200000 bs=1024 200000+0 records in 200000+0 records out 204800000 bytes transferred in 1.771045 secs (115637945 bytes/sec) Also, close to gigabit speeds... All is still good. But if I do # cat /dev/zero > /nfsbackup/test Its down to 25Mb/s Now, if this were consistent across all my boxes, I would not be too interested. Why is cat with a redirect so much slower, and why slower just on some boxes and not others ?!?! ---Mike -- ------------------- Mike Tancsa, tel +1 519 651 3400 Sentex Communications, mike@sentex.net Providing Internet services since 1994 www.sentex.net Cambridge, Ontario Canada http://www.tancsa.com/
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