Messages in this thread | | | Date | Thu, 19 Aug 2010 04:53:49 -0400 | From | Christoph Hellwig <> | Subject | Re: [RFC v3] ext4: Combine barrier requests coming from fsync |
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On Wed, Aug 18, 2010 at 07:07:34PM -0700, Darrick J. Wong wrote: > Oddly, I ran the entire suite of tests against a larger set of machines, and > with Tejun's RFC patchset I didn't see nearly as much of an improvement. I > have been trying to put together a new tree based on "replace barrier with > sequenced flush" and Christoph's "explicitly flush/FUA" patch sets, though I've > gotten lost in the weeds. :(
Tejun's patches don't allow concurrent cache flushes to happen, while my patch did. Tejun said there are drivers that can't handly empty flushes with a bio attached, making this nessecary.
Tejun, any idea what drivers that would be?
> I also experienced some sort of crash with Tejun's relaxed barrier patch on one > of my systems. I was hitting the BUG_ON in drivers/scsi/scsi_lib.c, line 1115.
My kernel source doesn't have a BUG_ON line there, but only one two lines above. A req->nr_phys_segments that's zero sounds a bit like empty flush requests, I'll need to look into it again.
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