Date: Sun, 11 Jun 2000 18:01:53 -0400 (EDT) From: David Gilbert <dgilbert@velocet.ca> To: freebsd-current@freebsd.org, freebsd-hackers@freebsd.org Subject: Worst case swapping. Message-ID: <14660.3153.658226.142964@trooper.velocet.net>
next in thread | raw e-mail | index | archive | help
I'm running a 700Mhz K7 with 256M of RAM as my workstation. I have two fast SCSI drives with a Gig of swap between them. The system shouldn't normally be a bottleneck as a workstation. I find, however, that there seem to be some bad worst-case senerios popping up rather often. Netscape is a good (common) example, but other memory stresses will show if the system is busy, too. What I'm talking about is a situation where some portion of the application will be swapped out and then when the application becomes active again, the swap will grind heavily reading and writing for 10-20 seconds (pushing 5M/s out and 5M/s in). Now the application in question (Netscape) usually runs around 50 to 75 megs, so that swapping activity is effectively swapping an amount of memory equavalent to the whole application out and then in again. My fear that this is a worst case scenario comes from this fact: that some other part of the application now-just-recently-active-again is being swapped out to bring in a part that was already swapped out. Now, you could argue that this case is hard to avoid, but I find this happening during periods of constant browsing ... such that only a small amount of the application could have been out. I'm positive that its not a case of the working set being larger than physical memory; it's one of choice of page to swap. Has anyone done any thinking about this behaviour? It occurs with varying degree to many applications. Dave. -- ============================================================================ |David Gilbert, Velocet Communications. | Two things can only be | |Mail: dgilbert@velocet.net | equal if and only if they | |http://www.velocet.net/~dgilbert | are precisely opposite. | =========================================================GLO================ 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?14660.3153.658226.142964>