Re: [Patch] SCSI statistics

Martin Peschke
2006-09-19T16:48:42Z

Matthew Wilcox wrote:
> On Mon, Sep 18, 2006 at 11:28:32PM +0200, Arjan van de Ven wrote:
>> wouldn't this be nicer as a block level functionality?
>
> We already have block layer statistics.

you mean disk_stats_read() etc. in genhd?

> What we don't have are stats
> that measure the other ways to send commands to scsi devices like SG and
> retries that the scsi system does without notifying the block layer. I
> think both are useful (although at first glance they seem redundant).

There are no statistics that allow to retrieve data similar to my patch,
with the exception of blktrace. But I think blktrace is difficult to use
as sole performance analysis tool on a customer's system with high load
and applications competing with blktrace postprocessing tools.