On 5/14/19 3:51 PM, Christoph Hellwig wrote:
On Tue, May 14, 2019 at 05:05:45PM +0800, Ming Lei wrote:
However we still may make it better, for example, the attached patch can
save 10~20% time when running 'mkfs.ntfs -s 512 /dev/vda', lots of small
request(63KB) can be merged to big IO(1MB).
And we could save even more time by making the block dev buffered I/O
path not do stupid things to start with.
With the gap devices we have unlimited segment size, see my next patch
to actually enforce that. Which is much more efficient than using
But this patch does effect on non-gap device, and actually most of
device are non-gap type.
Yes, but only for request merges, and only if merging the requests
goes over max_requests. The upside is that we actually get a
nr_phys_segments that mirrors what is in the request, fixing bugs
in a few drivers, and allowing for follow on patches that significantly
simplify our I/O path.
And we've seen several of these crashes in real life; signature is
'Kernel oops at drivers/scsi/scsi_lib.c:1003'.
So I'm really glad that this one is finally being addressed.
Thanks Christoph!
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@xxxxxxx +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
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