2.5 io statistics?

2.5 io statistics?

[Larry McVoy]

Is there a writeup of the changes anywhere?  I'd like to port cstat to 2.5.
Cstat is sort of a netstat/vmstat combo:

load free cach swap pgin  pgou dk0 dk1 dk2 dk3 ipkt opkt  int  ctx  usr sys idl
0.00  19M 562M  48M 4.0K   12K   0   0   0   0  137   25  267   83    0   0 100
0.00  18M 563M  48M   0    12K   0   0   0   0  133   22  258   77    0   1  99

-- 
---
Larry McVoy              lm at bitmover.com          http://www.bitmover.com/lm

Re: 2.5 io statistics?

[Andrew Morton]

Larry McVoy <lm@bitmover.com> wrote:
>
> Is there a writeup of the changes anywhere?  I'd like to port cstat to 2.5.
> Cstat is sort of a netstat/vmstat combo:
> 
> load free cach swap pgin  pgou dk0 dk1 dk2 dk3 ipkt opkt  int  ctx  usr sys idl
> 0.00  19M 562M  48M 4.0K   12K   0   0   0   0  137   25  267   83    0   0 100
> 0.00  18M 563M  48M   0    12K   0   0   0   0  133   22  258   77    0   1  99

It's currently undergoing a bit of change.

In 2.5.67 all IO activity is monitored by opening and reading
/sys/block/hda/stat.  This certainly doesn't scale when you have thousands of
disks, so there's a patch in -mm which performs runtime aggregation of global
stats and exposes that via /proc/diskstats.

So if you want to monitor the "global" IO activity, you don't need to open all
those sysfs files.

I don't know if the aggregate disk stats patch is ready to go yet.  I'm
awaiting testing results, conversion of userspace tools, etc.  I just plonked
it in there and haven't heard anything since.

As far as I know, neither the format of the sysfs file nor the format of
/proc/diskstats is documented anywhere.

Perhaps Rick can prepare a description for inclusion under Dcumentation/
somewhere?

Re: 2.5 io statistics?

[Rick Lindsley]

    As far as I know, neither the format of the sysfs file nor the format of
    /proc/diskstats is documented anywhere.
    
    Perhaps Rick can prepare a description for inclusion under Dcumentation/
    somewhere?

Happy to do so.  I will try to have it done within a week.

Rick

Re: 2.5 io statistics?

[Larry McVoy]

> > load free cach swap pgin  pgou dk0 dk1 dk2 dk3 ipkt opkt  int  ctx  usr sys idl
> > 0.00  19M 562M  48M 4.0K   12K   0   0   0   0  137   25  267   83    0   0 100
> 
> It's currently undergoing a bit of change.

Well, one question is this: I'd like to be able to get at a list of disk stats
sorted by activity.  If you noticed, the output above reserved space for 4
drives.  I know it's not general at all, but it would be nice to somehow be
able to get at the "busy" drives.  I don't have any ideas on how to do this
generally and that might mean it isn't possible but maybe (I hope) it means
I'm tired and not thinking clearly.  Anyone have any ideas?
-- 
---
Larry McVoy              lm at bitmover.com          http://www.bitmover.com/lm

Re: 2.5 io statistics?

[Pavel Machek]

Hi!

> > > load free cach swap pgin  pgou dk0 dk1 dk2 dk3 ipkt opkt  int  ctx  usr sys idl
> > > 0.00  19M 562M  48M 4.0K   12K   0   0   0   0  137   25  267   83    0   0 100
> > 
> > It's currently undergoing a bit of change.
> 
> Well, one question is this: I'd like to be able to get at a list of disk stats
> sorted by activity.  If you noticed, the output above reserved space for 4
> drives.  I know it's not general at all, but it would be nice to somehow be
> able to get at the "busy" drives.  I don't have any ideas on how to do this

Perhaps top-3 then sum of rest is better
idea (perhaps you do that already...)

-- 
				Pavel
Written on sharp zaurus, because my Velo1 broke. If you have Velo you don't need...