Messages in this thread | | | Subject | Re: Transparent compression in the FS | From | Chris Meadors <> | Date | Wed, 15 Oct 2003 22:11:31 -0400 |
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On Wed, 2003-10-15 at 14:54, root@mauve.demon.co.uk wrote:
> I haven't got the original message (mail problems) so I'm responding here. > > I misread your message, and thought you said compression. > My Duron 1300 (hardly the fastest machine) compresses (gzip -1) at around > 40Mb/sec (repetitive log-files that compress to 5% using gzip -1) and > 10Mb/sec on text (compressing to 40%). > > On expansion, it decompresses compressed text at around 14Mb/sec (resulting > in 30Mb/sec, around my disk speed), and logfiles at 110Mb/sec, which is > significantly faster. > > This is with a single stick of PC133 RAM, and a tiny 64K cache. > I would be very surprised if even a high end consumer machine couldn't handle > 50Mb/sec.
chris@prime:/tmp$ dd if=/dev/urandom of=random_data bs=1024 count=100k 102400+0 records in 102400+0 records out chris@prime:/tmp$ time gzip -9 random_data
real 0m10.572s user 0m10.271s sys 0m0.298s chris@prime:/tmp$ time gunzip random_data.gz
real 0m1.506s user 0m1.205s sys 0m0.301s chris@prime:/tmp$ time gzip -1 random_data
real 0m9.959s user 0m9.632s sys 0m0.326s chris@prime:/tmp$ time gunzip random_data.gz
real 0m1.523s user 0m1.218s sys 0m0.305s
chris@prime:/tmp$ dd if=/dev/zero of=zero_data bs=1024 count=100k 102400+0 records in 102400+0 records out chris@prime:/tmp$ time gzip -9 zero_data
real 0m2.947s user 0m2.812s sys 0m0.134s chris@prime:/tmp$ time gunzip zero_data.gz
real 0m1.062s user 0m0.920s sys 0m0.142s chris@prime:/tmp$ time gzip -1 zero_data
real 0m1.840s user 0m1.717s sys 0m0.123s chris@prime:/tmp$ time gunzip zero_data.gz
real 0m0.707s user 0m0.542s sys 0m0.165s
I can get pretty close to 50MB/sec compressing a nice long string of zeros. Over 100MB/sec decompressing the same. But from the first test, spinning my wheels on relatively uncompressible data gets me no where slowly.
Of course the disk subsystem of this machine is also a hardware RAID array of 8 (4 per channel) 10,000 RPM SCSI U320 drives. So I'm not approaching the speeds that I can get from it anyway.
-- Chris
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