Date: Wed, 5 Feb 2003 10:05:11 +0100 From: Brad Knowles <brad.knowles@skynet.be> To: phk@freebsd.org Cc: Brad Knowles <brad.knowles@skynet.be>, "Greg 'groggy' Lehey" <grog@freebsd.org>, current@freebsd.org Subject: Re: Preview: GEOMs statistics code. Message-ID: <a05200f06ba6683abf89c@[10.0.1.2]> In-Reply-To: <35259.1044435254@critter.freebsd.dk> References: <35259.1044435254@critter.freebsd.dk>
next in thread | previous in thread | raw e-mail | index | archive | help
At 9:54 AM +0100 2003/02/05, phk@freebsd.org wrote:
>> My understanding was that a disk is 100% busy, if the heads are
>>constantly moving to and fro, and there is no period of time when
>>they aren't being yanked around. In other words, it would be 100% if
>>there is always at least one outstanding request.
>
> Works for me, I'll try if I can instrument that cheaply.
I should be heading off to the office here shortly. Let me see
if I can quote the relevant sections of the iostat man page for
Solaris, with the hope that they will be able to explain more
accurately and clearly just exactly what it is that they measure and
what it means.
> I currently use binuptime() which means that the resolution is whatever
> the system provides, which means better than 1 microsecond on all current
> platforms.
>
> The counters are updated in real time, so it's up to you how often you
> read them.
So, we're talking about some fairly significant modifications to
iostat to get it to poll these values and be able to create some
averages that it can report.
> Well, "tracelog" is simply my word for the concept of recording
> each and every transaction and run it through some kind of analysis
> afterwards.
Ahh, I see.
Thanks again!
--
Brad Knowles, <brad.knowles@skynet.be>
"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety."
-Benjamin Franklin, Historical Review of Pennsylvania.
GCS/IT d+(-) s:+(++)>: a C++(+++)$ UMBSHI++++$ P+>++ L+ !E-(---) W+++(--) N+
!w--- O- M++ V PS++(+++) PE- Y+(++) PGP>+++ t+(+++) 5++(+++) X++(+++) R+(+++)
tv+(+++) b+(++++) DI+(++++) D+(++) G+(++++) e++>++++ h--- r---(+++)* z(+++)
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-current" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?a05200f06ba6683abf89c>