Date: Fri, 6 Nov 2009 20:01:16 +0100 From: Ivan Voras <ivoras@freebsd.org> To: Miroslav Lachman <000.fbsd@quip.cz> Cc: freebsd-fs@freebsd.org, freebsd-stable@freebsd.org Subject: Re: Performance issues with 8.0 ZFS and sendfile/lighttpd Message-ID: <9bbcef730911061101h5356d2acob2ac8791afe112@mail.gmail.com> In-Reply-To: <4AF46CA9.1040904@quip.cz> References: <772532900-1257123963-cardhu_decombobulator_blackberry.rim.net-1402739480-@bda715.bisx.prod.on.blackberry> <hcma4s$c49$1@ger.gmane.org> <4AEEBD4B.1050407@quip.cz> <hcmhbj$40s$1@ger.gmane.org> <4AEEDB3B.5020600@quip.cz> <hcmndo$q4e$1@ger.gmane.org> <4AF46CA9.1040904@quip.cz>
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2009/11/6 Miroslav Lachman <000.fbsd@quip.cz>: > I do not understand why there are 10MB/s read from disks when network > traffic dropped to around 1MB/s (8Mbps) > > root@cage ~/# iostat -w 20 > tty ad4 ad6 cpu > tin tout KB/t tps MB/s KB/t tps MB/s us ni sy in id > 0 14 41.66 53 2.17 41.82 53 2.18 0 0 2 0 97 > 0 18 50.92 96 4.77 54.82 114 6.12 0 0 3 1 96 > 0 6 53.52 101 5.29 54.98 108 5.81 1 0 4 1 94 > 0 6 54.82 98 5.26 55.89 108 5.89 0 0 3 1 96 Yes, this could limit your IO if the requests are random enough. Unfortunately I don't know how would you track down what is really going on. Maybe some tracing with DTrace? I'd tell you to use "top -m io" to see if there is a process responsible, but apparently these statistics are not updated for ZFS, which in itself may be a bug (which is why I'm crossposting to freebsd-fs).
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