Christoph Hellwig <hch@xxxxxxxxxxxxx> writes: > On Mon, Aug 23, 2010 at 10:47:55AM -0400, Chris Mason wrote: >> The aio batching code is using igrab to get an extra reference on the >> inode so it can safely batch. igrab will go ahead and take the global >> inode spinlock, which can be a bottleneck on large machines doing lots >> of AIO. >> >> In this case, igrab isn't required because we already have a reference >> on the file handle. It is safe to just bump the i_count directly >> on the inode. >> >> Benchmarking shows this patch brings IOP/s on tons of flash up by about >> 2.5X. > > There's some places in XFS where we do the same, and it showed up as a > bottle neck before. Instead of open coding the increment we have > a wrapper that includes and assert that the numbers is always positive. > > I think we really want a proper helper for general use instead of > completly opencoding it. Well, it would make detecting races or invalid assumptions a little easier. If Chris wants to code that up, that's fine with me. Honestly, though, I don't think it's necessary. I've gone through the alloc/free paths for the inode and I'm convinced this is safe. I'm happy with this version of the patch. Reviewed-by: Jeff Moyer <jmoyer@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
