Date: Sat, 06 Nov 1999 07:04:32 -0600 From: Rob Snow <rsnow@lgc.com> To: John-Mark Gurney <gurney_j@resnet.uoregon.edu> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: writing much slower than reading... Message-ID: <38242760.CA2CD9C@lgc.com> References: <9F147E391A3FD111B9A800805F356C52E25974@lgcadev001.zycor.lgc.com> <19991106043349.28321@hydrogen.fircrest.net>
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John-Mark, I'm sure that someone smarter than me can clear this up, but, we know that writing is rough. I can't understand a 8x difference, but again, there's probably a clear reason. From looking at the archives it looks like UDMA/66 (HPT/366 Controller) is only supported in UDMA/33 mode, in -current. I've got to admit that I probably didn't read your first post closely enough, I saw those numbers and cocked my head. Geez, I suddenly feel old... -Rob John-Mark Gurney wrote: > > Rob Snow scribbled this message on Nov 6: > [-- Warning: windows-1252 is not compatible with your display.] > > > Wow, I'm impressed! I bought the 10.1G 7200 last year for my Linux box, and > > I thought it was fast! Do me a favor, run Bonnie on it, with a 256M file. ( > > bonnie -s 256 ) > > > > Bonnie is in ports/benchmarks. > > running now... the numbers will be significantly slower because of the > slow processor on the machine... I can not max out the drive when I'm > going through the file system because the overhead is just to great... > when going through the file system, I see 99% usage by the system... > > the results: > # bonnie -s 256 > File './Bonnie.4177', size: 268435456 > -------Sequential Output-------- ---Sequential Input-- --Random-- > -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks--- > Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU > 256 9333 97.1 15535 96.5 4591 34.7 9101 97.5 17984 92.3 123.2 4.8 > > as you notice, both of the block input/output still have 90+% cpu usage.. > If I had a faster processor things would probably improve... but I'm > still quite a ways away from what rawio reports.... > > > Now, on to your problem, am I reading something wrong? It looks like your > > numbers are within 10% of each other. > > I should of been more specific... the problem is the system time, not > the actual speed of the drive... notice that when writing it uses 8 > times as much processor as when reading... > > it's interesting... rawio and dd use about 26% of the cpu to write to > the disk, (plus or minus a percent), rawio when reading uses about the > same cpu (slightly less), but dd when reading uses almost NO cpu, 3.6%.. > > the system should not have to do anything special, the worse would be > to break it down to 4kb, but that isn't happening else I would get even > worse performance (~12meg/sec)... and at 4kb, the processor isn't pegged > and neither is the drive, is this an IDE limitation?? do the default IDE > drivers not enable UDMA/66 which I know the MVP3 and the IBM drive > support? > > benchmarks: > # time rawio -c 128 -w /dev/rwd0s1g > Random read Sequential read Random write Sequential write > ID K/sec /sec K/sec /sec K/sec /sec K/sec /sec > anon 28706.9 438 > 38.42 real 0.64 user 9.47 sys > # time rawio -c 128 -r /dev/rwd0s1g > Random read Sequential read Random write Sequential write > ID K/sec /sec K/sec /sec K/sec /sec K/sec /sec > anon 29258.5 446 > 37.71 real 0.41 user 8.94 sys > # time dd if=/dev/zero of=/dev/rwd0s1g bs=64k count=16384 > 16384+0 records in > 16384+0 records out > 1073741824 bytes transferred in 50.254879 secs (21365922 bytes/sec) > 50.30 real 0.05 user 13.40 sys > # time dd if=/dev/rwd0s1g of=/dev/null bs=64k count=16384 > 16384+0 records in > 16384+0 records out > 1073741824 bytes transferred in 45.897254 secs (23394468 bytes/sec) > 45.90 real 0.03 user 1.61 sys > # time dd if=/dev/zero of=/dev/rwd0s1g bs=4k count=$((4*65536)) > 262144+0 records in > 262144+0 records out > 1073741824 bytes transferred in 85.742358 secs (12522887 bytes/sec) > 85.74 real 0.47 user 28.09 sys > > dmesg output: > wdc0 at 0x1f0-0x1f7 irq 14 flags 0xa0ffa0ff on isa > wdc0: unit 0 (wd0): <IBM-DPTA-372730>, DMA, 32-bit, multi-block-16 > wd0: 26105MB (53464320 sectors), 53040 cyls, 16 heads, 63 S/T, 512 B/S > wd0: ATA INQUIRE valid = 0007, dmamword = 0007, apio = 0003, udma = 041f > > > > John-Mark Gurney wrote: > > > > > > > > well, I am working on writing a capture program to do > > 640x480x12bpp@30fps > > > > to a raw disk, but writing to the raw device is SOOO slow... the reason > > > > I say it's slow is the fact that it takes 8 times the system time > > writing > > > > than reading... > > > > > > > > a bit about the system... k6/2-250, 100mhz system bus, pc100 64meg > > dimm, > > > > VIA MVP3 chipset (IDE DMA enabled), IBM-DPTA-372730 hard disk, Hauppauge > > > > WinCast/TV Model 61351 B226, 3.3-RELEASE... > > [benchmarks duplicated above] > > > > > now, why does it cost SOOO much more processing time to write than > > > > read?? are there plans to fix this slow down? is it possible? can't > > > > we just dma write out of userland since we are blocking on the write? > > -- > John-Mark Gurney Voice: +1 408 975 9651 > Cu Networking > > "The soul contains in itself the event that shall presently befall it. > The event is only the actualizing of its thought." -- Ralph Waldo Emerson > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-questions" in the body of the message To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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