Date: Fri, 12 Mar 2004 10:02:46 -0600 From: Dan Nelson <dnelson@allantgroup.com> To: Jimmy Olgeni <olgeni@uli.it> Cc: freebsd-questions@freebsd.org Subject: Re: about the "wdrain" state Message-ID: <20040312160246.GB37035@dan.emsphone.com> In-Reply-To: <20040312153634.O80001@dev1.localdomain.net> References: <20040312153634.O80001@dev1.localdomain.net>
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In the last episode (Mar 12), Jimmy Olgeni said: > When I move a lot of data on the disk (like untarring a new ports > collection or /usr/src/) the process works fine for a while, then > takes a long pause, then restarts again. When it "pauses", pressing > ^T shows it's in the "wdrain" state, which looks related to waiting > for the disk to finish some write operations. Unfortunately, the 5i > controller has a somewhat poor performance by itself so that may be > the cause. > > Are there any kernel tunables that I could change to at least > "spread" the pauses over many small intervals, rather than locking > the process for a few seconds? The volume is using softupdates, I > thought about changing kern.filedelay and friends but I'd like to > know if there are sensibile values to put in before I fry the > production server :) Depending on how much memory you have, I think raising vfs.hirunningspace might help here. It will allow more write buffers to build up before the system decides it needs to flush some. Take a look at the waitrunningbufspace() function in /sys/kern/vfs_bio.c, or do a web search for "hirunningspace" -- Dan Nelson dnelson@allantgroup.com
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