From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 13 May 2002 12:08:09 -0400 (EDT) From: Bill Davidsen Subject: Re: [RFC][PATCH] IO wait accounting In-Reply-To: <87bsbl9ogw.fsf@atlas.iskon.hr> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Zlatko Calusic Cc: Rik van Riel , linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: On Sun, 12 May 2002, Zlatko Calusic wrote: > Rik van Riel writes: > > > > And should we measure read() waits as well as page faults or > > just page faults ? > > > > Definitely both. Somewhere on the web was a nice document explaining > how Solaris measures iowait%, I read it few years ago and it was a > great stuff (quite nice explanation). I'm out of town so I miss a bit of this, but I agree, what you want time waiting for IO, total. That said, it would probably be useful to keep the first patch information, since overall disk performance reflects in total IOwait, while wait VM is useful comparing the several flavors of vm tuning and enhancement, bot the the implementors and the users, who may have unusual configurations. I hope that write blocks are falling into place as well, because even though they are less common, you still get programs which build ugly stuff like a full 700MB CD image in memory and do that last write (or close, or fsync, etc). This is bad with large memory, and unspeakable with small, where stuff is being paged in and writen out. -- bill davidsen CTO, TMR Associates, Inc Doing interesting things with little computers since 1979. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/