Date: Sat, 6 Nov 1999 12:01:58 -0800 From: John-Mark Gurney <gurney_j@efn.org> To: Jonathan Lemon <jlemon@americantv.com> Cc: hackers@freebsd.org Subject: Re: writing much slower than reading... Message-ID: <19991106120158.26688@hydrogen.fircrest.net> In-Reply-To: <199911061708.LAA25924@free.pcs>; from Jonathan Lemon on Sat, Nov 06, 1999 at 11:08:58AM -0600 References: <local.mail.freebsd-hackers/19991106013045.13836@hydrogen.fircrest.net> <199911061708.LAA25924@free.pcs>
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Jonathan Lemon scribbled this message on Nov 6:
> Try doing `iostat 1' while doing the transfers. This is what I see here:
>
> tty da0 da1 da2 cpu
> tin tout KB/t tps MB/s KB/t tps MB/s KB/t tps MB/s us ni sy in id
> TEST A: 0.00 0 0.00 64.00 119 7.47 0.00 0 0.00 0 0 3 0 97
> TEST B: 0.00 0 0.00 64.00 419 26.18 0.00 0 0.00 0 0 1 0 99
> TEST C: 0.00 0 0.00 64.00 95 5.94 64.00 95 5.94 0 0 1 0 99
> TEST D: 63.84 338 21.05 64.00 343 21.41 0.00 0 0.00 0 0 26 2 72
>
> TEST A: (writing) dd if=/dev/zero of=/dev/rda1 bs=1m count=400
> TEST B: (reading) dd if=/dev/rda1 of=/dev/zero bs=1m count=400
> TEST C: (read & write) dd if=/dev/rda1 of=/dev/rda2 bs=1m count=400
> TEST D: (read raw & write fs) dd if=/dev/rda1 of=trash bs=1m count=400
tty wd0 cpu
tin tout KB/t tps MB/s us ni sy in id
TEST A: 113.50 182 20.19 0 0 27 1 72
TEST B: 113.63 202 22.41 0 0 2 2 96
TEST C: 114.07 174 19.40 0 0 2 1 97
TEST D: 81.92 224 17.89 0 0 48 3 48
since I only have on drive, TEST C was dd of=/dev/rwd0s1g
if=/dev/rwd0s1g bs=1m count=400, and TEST D was writing to the same
drive that I was reading from, no softupdates enabled... and I was
doing all testing on /dev/rwd0s1g so I could write...
> System is a Dell Poweredge 4300 PIII/600, all disks are Seagate ST39103LC.
k6-2/250 (100mhz system bus), IBM-DPTA-372730
> Disk da0 (where the trash file is written) has softupdates enabled. This
> is on a week old -current.
>
> I'm suprised by the last line. Writing to the filesystem is faster
> than writing to the raw device? I must be missing something here.
I'm surprised at the last two lines... I didn't think that I would be
able to push/pull that much data at once, but considering that it didn't
have to seek far it isn't that surprising...
hmmmm... could this be a deficency in the IDE driver?? sounds like I
need to test the new ata driver and see if it performs better...
--
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
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