Date: Wed, 14 Dec 2005 16:17:38 -0700 From: Scott Long <scottl@samsco.org> To: Kevin Oberman <oberman@es.net> Cc: stable@freebsd.org Subject: Re: Odd performance problems after upgrade from 4.11 to 6.0-Stable Message-ID: <43A0A812.1060104@samsco.org> In-Reply-To: <20051214222037.94FEF5D07@ptavv.es.net> References: <20051214222037.94FEF5D07@ptavv.es.net>
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Kevin Oberman wrote: > I recently upgraded my last desktop system from 4.11-Stable to > 6.0-Stable. I did an update to 5.3 then to RELENG_5, > RELENG_6_0_0_RELEASE and on to RELENG6_0. > > This system has been updated regularly from the days of at least 4.1. > The hardware is a 1GHz PIII with an ICH2 chipset. 256 MB of memory. > > After the upgrade, the system performs poorly. Specifically, it seems to > be blocking on I/O. If I have a dump or bsdtar running, a CPU intensive > job produced minimal CPU utilization and little progress. The system is > 70% or more idle all of the time. X is particularly sluggish. Many times > the system will simply appear to be locked up for seconds at a time like > all of the I/O is synchronous and the entire system is blocking on GIANT > until the disk write finishes. A level 0 dump of the system drive piped > through gzip and over the network took about 10 hours. Now it is 17 > hours. My network link only ran at 3.4 Mbps (yes, that's bits, not > Bytes) over a 100 Mbps connection to the storage server. The rate was > much higher under 4.11. > > My attempts to track down the source of the problem simply failed. I > have examined my kernel configuration and found nothing out of the > ordinary. In fact, the the configuration varies from GENERIC only in > devices (both added and deleted), dropping 486 and 586 CPU code and a > larger SC_HISTORY. I have nothing in sysctl.conf and only enable DMA on > my ATAPI devices in loader.conf. I have confirmed that the disks are > running ATA100. > > Any suggestions on where to look? At this point I am baffled. The bufdaemon is probably causing some of the Giant contention. However, what it is contending with is the real question. Is your network driver and stack running MPSAFE? At least a 'dmesg' dump is needed here. Also, taking out CPU_I586 is usually a bad idea. It offers no performance penalties (unlike CPU_I386 and maybe CPU_I486), but enables things like optimized bcopy. Scott
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