Re: iostat - multiblock read count

Fabrizio wrote:

> I had a look at the associated bug on metalink. It seems the limit of
> 32K involves only i/o on raw and OCFS of a specific redhat version.

Not sure. Its symptoms appear to show up in at least my RH test box and I'm not running raw or OCFS...

> As a test I took an old vanilla kernel (2.4.12) and performed the
> previous dd (always on ext3 and reiserfs). The limit is not there and
> the asynch i/o is doing its duty.

'sOK with SLES, AFAIK. (yay!)

> May I ask you the sources of your statement about a 2.4 "design limit"?
> (I'd like to invastigate this further: so far it smmes a myth).

The pdf document I pointed out plus the blurb in the RH bugzilla. I'd say it's similar to the old Unix limit on max IO size: used to be 64K, then some makers bumped it up to 1M.

> Thank you. The document (and the related ones) is really useful.

Pleasure. Please let me know of anything you find: running RH and this could have a big impact for me in the near future. Here or via email in the header. I'm going to find this particular module in the source and see if I can figger who/what runs when. That should show what's going on. Gotta load the RH sources first, across the bigpond: s-l-o-w... Received on Wed May 25 2005 - 04:26:57 CDT