Messages in this thread | | | Date | Mon, 20 Jan 2014 05:58:55 -0800 | From | Christoph Hellwig <> | Subject | Re: Terrible performance of sequential O_DIRECT 4k writes in SAN environment. ~3 times slower then Solars 10 with the same HBA/Storage. |
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On Thu, Jan 16, 2014 at 09:07:21AM +1100, Dave Chinner wrote: > Yes, I think it can be done relatively simply. We'd have to change > the code in xfs_file_aio_write_checks() to check whether EOF zeroing > was required rather than always taking an exclusive lock (for block > aligned IO at EOF sub-block zeroing isn't required),
That's not even required for supporting aio appends, just a further optimization for it.
> and then we'd > have to modify the direct IO code to set the is_async flag > appropriately. We'd probably need a new flag to say tell the DIO > code that AIO beyond EOF is OK, but that isn't hard to do....
Yep, need a flag to allow appending writes and then defer them.
> Christoph, are you going to get any time to look at doing this in > the next few days?
I'll probably need at least another week before I can get to it. If you wanna pick it up before than feel free.
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