Red Hat Bugzilla – Bug 102194
Disk READ performance worse compared with 2.4.20-18.9smp
Last modified: 2007-11-30 17:06:57 EST
Description of problem:
I am using Fujitsu MAP3735NC or MAP3367NC disks. In case of
kernel 2.4.20-18.9smp I am using from people.freebsd.org/~gibbs/linux
the driver aic79xx 1.3.11. Now I compared the diskperformance for this
kernel with the performance for kernel 2.4.21-1.1931.2.382entsmp.
Write performance was for both kernels the same, but read performance
was for 2.4.20-18.9 approx. 64 mb/sec while for 2.4.21-... the performance
was 35 mb/sec
Version-Release number of selected component (if applicable):
Always, also reproducible with maxtor disks
Steps to Reproduce:
1.get attachment for bug 101938
2.create executable rio with make -f Makefile.linux
3.run the program, with e.g. ./rio -s 8g -b 320k -t -d .
This will create with seq. write a file : size 8 gb, used blocksize 320k
working directory = current directory
I will create another bug for aic79xx with fujitsu disks
What version of RHEL beta kernel were you testing against? Please also test
with the latest kernels available in sushi.
Sorry being so late with the answer, I can add now some more details
the IO performance is independant from the SCSI controller.
I tried AIC7902 and LSI sym53c8xx in both cases the read performance
is close to 60 mb/sec when I use rh 9.0 with kernel 2.4.20-18.9smp
and it is just 40 mb/sec when I use rh 9.0 with
kernel 2.4.21-1.1931.2.414.entsmp ( from rhel 3.0 beta 2 ws i386 )
could you do a 'vmstat 1 > vmstat.log' during the rio testrun and attach the
results here - are the writes steady?
Created attachment 94553 [details]
vmstat for rh 9.0 with kernel 2.4.20-18.9smp
Here are the requested output files ( vmstat 1 ) for READ of rio.
Note : Adaptec provides now new drivers for aic79xx
This run was done using aic79xx-2.0.2
while it probably doesn't matter in this case, I would like to urge you to ONLY
report bugs with drivers we shipped.
Created attachment 94554 [details]
output of vmstat 1 for kernel 2.4.21-1.1931.2.423entsmp
can you check if it gets better if you do
echo 127 > /proc/sys/vm/max-readahead
The problem is not the WRITE, the write is almost the same for both kernels,
but the READ is better for the kernel 2.4.20-18.9smp. On the 2.4.21 kernel the
READ performance is worse even compared with the WRITE performance. I think,
that for an EXT3 filesystem seq. READ must be better than WRITE.
The read performance is now improved, 47.5 mb/sec instead of 43 mb/sec.
But in case of 2.4.20-18.9smp I had 54 mb/sec.
The note with the new driver was just an information, that rh should consider
this driver for the new kernels .
*** This bug has been marked as a duplicate of 104633 ***
An errata has been issued which should help the problem described in this bug report.
This report is therefore being closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files, please follow the link below. You may reopen
this bug report if the solution does not work for you.