Re: mpt fusion driver performance issue in 2.6.14-rc2
Moore, Eric Moore <Eric.Moore <at> lsil.com>
2005-10-01 06:19:56 GMT
On Friday, September 30, 2005 6:27 PM, Chen, Kenneth W wrote:
> Chen, Kenneth W wrote on Thursday, September 29, 2005 11:59 AM
>> Something happened in between kernel 2.6.12 and 2.6.14-rc2, where
>> disk performance went 20X slower on the latest release kernel. I
>> suspect it has something to do with the fusion driver. This showed
>> up in the boot log: "mptscsih: ioc0: DV: Release failed." is it
> I think the bug is for real, and it is in the mpt fusion driver. I'm
> not an expert of LSI53C1030 host controller, and I won't pretend to be
> one. Though I have data to show what is going on:
> There are two threads during driver initialization. One does domain
> validation (mptscsih_domainValidation) and one does host controller
> initialization (mptspi_probe). During 2nd host controller bringup,
> i.e., bringing up ioc1, it temporary disables first channel (ioc0).
> However, DV is in progress on ioc0 in another thread (and possibly
> running on another CPU). The effect of disabling ioc0 during in-
> progress-domain-validation is that it causes all subsequent DV
> commands to fail and resulting lowest possible performance setting
> for almost all disks pending DV.
> Here is a fix that I propose: for the period that ioc0 need to be
> disabled for bringing up ioc1, ioc->active is marked with a special
> flag and have DV thread busy wait on that flag. This avoid mptspi_probe
> thread clash into the DV thread causing brain-damage to DV.
> With the patch, all disks are up to the performance expectation and it
> also fixed the "mptscsih: ioc0: DV: Release failed" error message.