addjust discard request to be aligned with hwsect size to support SSDs with larger sector size
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From: Martin K. Petersen on 17 May 2010 16:10 >>>>> "Jiaying" == Jiaying Zhang <jiayingz(a)google.com> writes: Jiaying> It is true that all of the block layer works on 512-byte sector Jiaying> size, but I think it is good to check for address alignment for Jiaying> discard request so we don't insert unnecessary discard requests Jiaying> into the request queue. Well, then what happens when you stripe or use DM on devices with different discard granularity? Or what about a mirror? Or multiple levels of stacking of heterogeneous devices. There are good reasons why we postpone the logical block scaling until we're preparing the request for the actual physical device. Jiaying> There are also certain disk drivers that assume a discard Jiaying> request passed from the block layer is already properly Jiaying> aligned. We could argue that those disk drivers need to fix Jiaying> that Which is what I'm arguing :) Jiaying> 512 bytes and 4KB seem to be the most common sizes but I Jiaying> wouldn't be surprised to see other logical block size. That's the reason I'm asking. If you have a different lbs then let's by all means add support for it. Or make the ULD scaling generic. I'm open to aligning to the reported discard granularity in the ULD, for instance. -- Martin K. Petersen Oracle Linux Engineering -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |