topic Re: can't find the "low_io_sectors" and "high_io_sectors" in /proc/sys/vm in Operating System - Linux

can't find the "low_io_sectors" and "high_io_sectors" in /proc/sys/vm

richeal75 — Thu, 19 May 2005 06:30:43 GMT

hello ,

Now I want to adjust kernel parameter as below:
echo 2000 > /proc/sys/vm/low_io_sectors
echo 4000 > /proc/sys/vm/high_io_sectors

but i can't find them in /proc/sys/vm .

os: redhat AS 2.1
my kernel: 2.4.9-e3smp
url:
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=85231

Re: can't find the "low_io_sectors" and "high_io_sectors" in /proc/sys/vm

Gopi Sekar — Thu, 19 May 2005 06:56:36 GMT

i check on my 2.6 kernel but couldnt find one either. but i think they have changed a lot from 2.4 to 2.6, nevermind.

check up through sysctl, try one of these to find which one succeeds.

sysctl proc.sys.vm.low_io_sectors
sysctl proc.stat.low_io_sectors
sysctl proc.sys.low_io_sectors

if any of them succeed and outputs the value then set them using sysctl -p, for further information check 'man sysctl'

Regards,
Gopi

Re: can't find the "low_io_sectors" and "high_io_sectors" in /proc/sys/vm

Stuart Browne — Thu, 19 May 2005 08:06:33 GMT

Direct quote from the URL you posted:

What we have done in 2.4.9-e.12

i.e. a different kernel revision. Update to at least that kernel revision, and try again.

I know that option isn't available on my FC box running a 2.4 series kernel.

Re: can't find the "low_io_sectors" and "high_io_sectors" in /proc/sys/vm

richeal75 — Thu, 19 May 2005 10:17:18 GMT

Gopi Sekar & Stuart Browne :

thanks for yours help !

As I'm beginner of Redhat Linux , I want to know how to upgrade my Redhat AS 2.1 with kernel 2.4.9-e3smp to 2.4.9-e12smp.

pls advise a simple way !

thanks again !

Re: can't find the "low_io_sectors" and "high_io_sectors" in /proc/sys/vm

Gopi Sekar — Thu, 19 May 2005 10:41:44 GMT

The simplest way would be to use up2date utility with RHN subscription. then you can use this utility to update all the packages in your system including kernel or you can specify which paackage you want update and get them updated.

Also the 2.4.9-e12 kernel is outdated and there is a new kernel which includes this fix along with few other fixes, check out the following link about it.
http://rhn.redhat.com/errata/RHSA-2005-283.html

the above link also gives instruction on how to upgrade the kernel from command line.

anyway even to download the kernel manually you need to have RHN subscription.

Regards,
Gopi

Re: can't find the "low_io_sectors" and "high_io_sectors" in /proc/sys/vm

richeal75 — Thu, 19 May 2005 23:34:18 GMT

Hello ,

I can find "low_io_sectors" and "high_io_setcotrs" in /proc/sys/vm after i upgrade kernel from 2.4.9-e3 to 2.4.9-e62

and then I adjust them as below:

echo 2000 /proc/sys/vm/low_io_sectors
echo 4000 /proc/sys/vm/high_io_sectors

and then result is ok as below

2000 /proc/sys/vm/low_io_sectors
4000 /proc/sys/vm/high_io_sectors

and I run " more /proc/sys/vm/low_io_sectors"
but I find the value is not changed

why ?

Re: can't find the "low_io_sectors" and "high_io_sectors" in /proc/sys/vm

Gopi Sekar — Mon, 23 May 2005 01:30:45 GMT

you forgot to add '>' symbol

it should be like this:

echo 2000 > /proc/sys/vm/low_io_sectors

Hope this helps,
Gopi