Date: Sun, 8 Aug 1999 14:01:37 -0700 (PDT) From: Julian Elischer <julian@whistle.com> To: brian@pobox.com Cc: Brian McGroarty <BMCGROARTY@high-voltage.com>, freebsd-hardware@FreeBSD.ORG Subject: Re: The $500 Performance Question Message-ID: <Pine.BSF.3.95.990808135805.9024B-100000@current1.whistle.com> In-Reply-To: <19990807051505.3696.rocketmail@web1003.mail.yahoo.com>
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On Fri, 6 Aug 1999, Brian McGroarty wrote: > Moving from the old wd driver to the new ata made very, very > little difference. Soft updates shaved about 10 minutes off the > build however. > > I don't believe more RAM will buy me anything as I'm already at > 512 and I don't think the free section dips under 200 during > make world. > > I'm not sure I see where building objects to another drive would > help either with lazy writes/soft updates on since the entire > block of files to be written easily fits within RAM. the writes to disk get in the way of the reads of needed source files therefore the CPU stalls, hence idle time.. > > I'm also of the opinion that reading ahead in the make file > won't make a tremendous difference if I'm using "make -j 40 > world" as there should most always be a task ready to run while > the read operation waits to complete on a stalled thread. No, most of the processes will be waiting for souce most of the time.. > > Interestingly, despite there only being a (roughly) 15% decrease > in time, CPU usage jumps tremendously. Most of the time I'm > averaging about 20% free on one CPU and as little as 5% on the > other. I'll be curious to look at the soft update code - I > wonder if that's coded as efficiently as it could be. it trades CPU/memory for IO. > > > --- Julian Elischer <julian@whistle.com> wrote: > > ensure that all output is to different drives and a different > > controller > > from the source. use soft updates, (or async if the output > > drive is > > expendable). use -current. possibly modify each makefile at a > > medium > > level to preread the sources so they are in cache (and use the > > money to > > add more RAM). The disks should be DMA and the trick is to > > make sure that > > everything is already in RAM. > > > > On Fri, 6 Aug 1999, Brian McGroarty wrote: > > > > > I've got a PC used primarily for programming. Projects tend > > to be large (8-12 > > > megs of C++ source), so build time is a concern. I'd like > > ideas on where the > > > best place to sink $500 would be to boost performance. > > > > > > Relevant in the current configuration: > > > > > > o (2) Celeron 300a (on socket converters, overclocked to > > 500mhz) > > > o Tyan Tiger 100 motherboard (Dual CPU) > > > o 512mb 100mhz RAM > > > > > > EIDE controller: > > > o 14 gig 7200 EIDE (/usr,/,swap) > > > o 28 gig 7200 EIDE (/tobackup,/cvs) > > > > > > EIDE controller 1: > > > o 14 gig 7200 EIDE (/home) > > > o 2/8x CDRW/CD-ROM > > > > > > For a familiar benchmark, a FreeBSD 'make world -j 40' takes > > about an hour > > > and ten minutes. This may be slewed against your ssytem by > > the inclusion of > > > -O3 optimization. > > > > > > The CPUs realize a lot of idle time; upward of 60%. I expect > > then that I/O is > > > my main bottleneck. > > > > > > The drives are Ultra-66 capable, but I don't believe FreeBSD > > supports this at > > > current. Thus, I don't see a way to enhance what I've got. > > (I'm already > > > enabling 32-bit and DMA on the controllers via flags). > > > > > > So what's my best bet? Is there a fast and economical SCSI-2 > > controller and > > > drive I should try? Any supported IDE RAID controllers? Or > > is there an > > > Ultra-66 controller FreeBSD merely sees as really fast EIDE? > > > > > > Or is this time being spent in the huge kernel lock? Would > > CAS2 capable RAM > > > then perhaps speed the buffer transfers noticably and get > > the CPUs back to > > > unmanaged portions more quickly? > > > > > > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > > > with "unsubscribe freebsd-hardware" in the body of the > > message > > > > > > > > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > > with "unsubscribe freebsd-hardware" in the body of the message > > > > > > _____________________________________________________________ > Do You Yahoo!? > Bid and sell for free at http://auctions.yahoo.com > > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message
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