On Fri, 18 Jan 2008, Martin Knoblauch wrote: > > just to make one thing clear - I am not so much concerned about the > performance of AACRAID. It is OK with or without Mel's patch. It is > better with Mel's patch. The regression in DIO compared to 2.6.19.2 is > completely independent of Mel's stuff. > > What interests me much more is the behaviour of the CCISS+LVM based > system. Here I see a huge benefit of reverting Mel's patch. Ok, I just got your usage cases confused. The argument stays the same: some controllers/drivers may have subtle behavioural differences that come from the IO limits themselves. So it wasn't AACRAID, it was CCISS+LVM. The argument is the same: it may well be that the *bigger* IO sizes are actually what hurts, even if the conventional wisdom is traditionally that bigger submissions are better. > At least, rc1-rc5 have shown that the CCISS system can do well. Now > the question is which part of the system does not cope well with the > larger IO sizes? Is it the CCISS controller, LVM or both. I am open to > suggestions on how to debug that. I think you need to ask the MD/DM people for suggestions.. Who aren't cc'd here. Linus - To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
