Re: Odd behavior of xfs with SCSI/Adaptec AIC7899

[Steve Lord <lord@sgi.com>]

Hi, first of all, turn off write caching on the ide device and try 
again, it will get a lot slower:

	hdparm -W 0 /dev/hda

Second, get a recent xfs kernel, delete speed has been improved.

Steve

On Wed, 2002-03-13 at 14:20, Qing Liu wrote:
> Hello,
> 
> I did a very simple test sometimes ago on deleting files and found that it
> is much slower on SCSI than on IDE drive !
> 
> Box 1: Bi-Pentium III 1Ghz, 256 MB Ram, hard drive SCSI FUJITSU UW2, 18 GB, 
> Adaptec AIC 7899, hdparm -t /dev/sda:  52.89 MB/sec
> Test partition is /dev/sda3, 5.9 GB.
> Software: RedHat 7.2, with vanilla kernel 2.4.16 + patches xfs-2.4.16-all-i386
> and jfs-1.0.14, compiled with egcs 1.1.2. Test partition is /dev/sda3, 5.9 GB.
> 
> Box 2: Duron 700 Mhz, 128 Mo, hard drive IDE Western Digital Udma66, 20 GB
> hdparm -t 20.98 MB/sec. Test partition is /dev/hda10, 3.6 GB.
> Software: Slackware 8.0, vanilla kernel 2.4.16 + patches xfs-2.4.16-all-i386
> and jfs-1.0.14, compiled with gcc-2.95.3.
> 
> 
> The test consist in formatting the test partition, copying the source of the 
> kernel into the test partition, umounting the partition, and then
> deleting the copied source tree.
> 
> Results of time rm -rf /testfs/LINUX; time sync
> 
> Box 1:
> 
> ---------------------------------------------------------------------------------
>            ext2          ext3            reiserfs         xfs             jfs
> ---------------------------------------------------------------------------------
> real      6.972s        7.245s          3.086s          1m17.333s       48.510s
> user      0.020s        0.010s          0.050s             0.070s        0.030s
> sys       0.180s        0.540s          1.210s             2.640s        0.800s
> sync real 0.616s        0.569s          0.165s             0.014s        0.039s
> ---------------------------------------------------------------------------------
> 
> Box 2:
> 
> ---------------------------------------------------------------------------------
>           ext2           ext3            reiserfs         xfs             jfs
> ---------------------------------------------------------------------------------
> real      4.907s        7.416           4.242s          15.415s         15.005s
> user      0.050s        0.020           0.060s           0.120s          0.110s
> sys       0.230s        0.820           1.480s           3.610s          0.960s
> ----------------------------------------------------------------------------------
> 
> The test had been running several times with comparable output.
> 
> I known xfs is rather slow when deleting large number of files (above 11,000 
> here). But it is rather surprising that it performs *much worse* on a much
> better machine. The problem is same with a mono processor kernel on Box 1.
> 
> Is there a known issue here ?
> 
> Liu
> 
> 
-- 

Steve Lord                                      voice: +1-651-683-3511
Principal Engineer, Filesystem Software         email: lord@sgi.com