Strange -- my times stays about the same:
$ time ./xlog aa fsync
real 0m23.695s
user 0m0.020s
sys 0m0.150s
$ time ./xlog aa fsync
real 0m24.024s
user 0m0.030s
sys 0m0.130s
$ rm aa
$ time ./xlog aa fsync
real 0m23.979s
user 0m0.020s
sys 0m0.140s
$ time ./xlog aa xxx
real 0m0.009s
user 0m0.000s
sys 0m0.010s
Trying another disk, I get:
$ time ./xlog /tmp/aa xxx
real 0m0.012s
user 0m0.010s
sys 0m0.000s
$ time ./xlog /tmp/aa fsync
real 0m12.673s
user 0m0.000s
sys 0m0.040s
$ rm /tmp/aa
$ time ./xlog /tmp/aa fsync
real 0m12.617s
user 0m0.000s
sys 0m0.030s
----------
$ time ./xlog /home/ftp/pub1/aa xxx
real 0m0.021s
user 0m0.000s
sys 0m0.010s
$ time ./xlog /home/ftp/pub1/aa fsync
real 0m15.853s
user 0m0.010s
sys 0m0.130s
$ rm /home/ftp/pub1/aa
$ time ./xlog /home/ftp/pub1/aa fsync
real 0m15.901s
user 0m0.010s
sys 0m0.180s
----------
/dev/sdc2 10082156 9399520 170484 98% /home/karl
/dev/sda7 297469 254 281856 0% /tmp
/dev/sdb1 25197660 19723280 4194384 82% /home/ftp/pub1
So I get what the common sense tells you, full disk - long time.
My "real" run time does not depend on if file is present or not.
The run time for empty partion is still 12s, compared to ~2s for IDE
(reported earlier in this thread by "Jeremy Hansen"
<[EMAIL PROTECTED]>).
(lk2.2.18 with sym-2.1.0-20001230 driver)
Regards,
/Karl
-----------------------------------------------------------------------
Karl Hammar Aspö Data [EMAIL PROTECTED]
Lilla Aspö 2340 +46 173 140 57 Networks
S-742 94 Östhammar +46 10 270 26 67 Computers
Sweden Consulting
-----------------------------------------------------------------------
From: Ishikawa <[EMAIL PROTECTED]>
Subject: Re: scsi vs ide performance on fsync's
Date: Mon, 05 Mar 2001 06:28:49 +0900
> Douglas Gilbert wrote:
>
> > There is definitely something strange going on here.
> > As the bonnie test below shows, the SCSI disk used
> > for my tests should vastly outperform the old IDE one:
>
> First thank you and others with my clueless investigation about
> the module loading under Debian GNU/Linux. (I should have known
> that Debian uses a very special module setup.)
>
> Anyway, I used to think SCSI is better than IDE in general, and
> the post was quite surprising.
> So I ran the test on my PC.
> On my systems too, the IDE beats SCSI hand down with the test case.
>
> BTW, has anyone noticed that
> the elapsed time of SCSI case is TWICE as long if
> we let the previous output of the test program stay before
> running the second test? (I suspect fdatasync
> takes time proportional to the (then current) file size, but
> still why SCSI case is so long is beyond me.)
>
> Eg.
>
> ishikawa@duron$ ls -l /tmp/t.out
> ls: /tmp/t.out: No such file or directory
> ishikawa@duron$ time ./xlog /tmp/t.out fsync
>
> real 0m38.673s <=== my scsi disk is slow one to begin with...
> user 0m0.050s
> sys 0m0.140s
> ishikawa@duron$ ls -l /tmp/t.out
> -rw-r--r-- 1 ishikawa users 112000 Mar 5 06:19 /tmp/t.out
> ishikawa@duron$ time ./xlog /tmp/t.out fsync
>
> real 1m16.928s <=== See TWICE as long!
> user 0m0.060s
> sys 0m0.160s
> ishikawa@duron$ ls -l /tmp/t.out
> -rw-r--r-- 1 ishikawa users 112000 Mar 5 06:20 /tmp/t.out
> ishikawa@duron$ rm /tmp/t.out <==== REMOVE the file and try again.
> ishikawa@duron$ time ./xlog /tmp/t.out fsync
>
> real 0m40.667s <==== Half as long and back to original.
> user 0m0.040s
> sys 0m0.120s
> iishikawa@duron$ time ./xlog /tmp/t.out xxx
>
> real 0m0.012s <=== very fast without fdatasync as it should be.
> user 0m0.010s
> sys 0m0.010s
> ishikawa@duron$
>
>
> -
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