Date: Wed, 31 Oct 2007 23:30:04 GMT From: John Baldwin <jhb@FreeBSD.org> To: freebsd-amd64@FreeBSD.org Subject: Re: amd64/117664: iostat can't display IO current vlaue in first line Message-ID: <200710312330.l9VNU4Uq062886@freefall.freebsd.org>
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The following reply was made to PR amd64/117664; it has been noted by GNATS. From: John Baldwin <jhb@freebsd.org> To: freebsd-amd64@freebsd.org Cc: chifeng <chifeng@gmail.com>, freebsd-gnats-submit@freebsd.org Subject: Re: amd64/117664: iostat can't display IO current vlaue in first line Date: Wed, 31 Oct 2007 13:53:35 -0400 On Tuesday 30 October 2007 03:22:39 am chifeng wrote: > > >Number: 117664 > >Category: amd64 > >Synopsis: iostat can't display IO current vlaue in first line > >Confidential: no > >Severity: non-critical > >Priority: low > >Responsible: freebsd-amd64 > >State: open > >Quarter: > >Keywords: > >Date-Required: > >Class: change-request > >Submitter-Id: current-users > >Arrival-Date: Tue Oct 30 07:30:02 UTC 2007 > >Closed-Date: > >Last-Modified: > >Originator: chifeng > >Release: FreeBSD6.2-Release-p8 > >Organization: > Platform Computing > >Environment: > FreeBSD cnxabuild.asia.corp.platform.com 6.2-RELEASE-p8 FreeBSD 6.2-RELEASE-p8 #0: Tue Oct 16 12:32:14 CST 2007 root@xabuild.asia.corp.platform.com:/usr/obj/usr/src/sys/PLATFORM amd64 > >Description: > When I write a shell script plugin for munin, I hope get a current value of IO statistics. But iostat can't do it, it first statistics that are printed are avaraged over the system uptime. If I use "iostat -c 2 | tail -1 " command, this will wait 2s at least. > so I think for iostat first line, 1) iostat should be display current value, 2) have a parameter to display current value at least. There isn't a 'current value' for iostat to dump. The kernel just keeps running counts and iostat simulates a current value by saving the values each time and computing a delta for each line after the first. However, for the first line there is no saved value so it cannot compute a delta. Probably you need to write your own plugin that saves the previous values and computes deltas when queried similar to how iostat behaves. -- John Baldwinhome | help
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