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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Fri, Oct 25, 2019 at 01:05:40PM +0900, Keith Busch wrote: > On Thu, Oct 24, 2019 at 11:30:18AM +0000, Mark Ruijter wrote: > > Note that I wrote this patch to prove that a performance problem exists when using raid1. > > Either the md raid1 driver or the io-cmd-bdev.c code has issues. > > When you add an additional layer like the VFS the performance should typically drop with 5~10%. > > However in this case the performance increases even though the nvme target uses direct-io and the random writes do not get merged by the VFS. > > Are we really using direct io when nvme target is going through vfs, > though? That should happen if we've set IOCB_DIRECT in the ki_flags, > but I don't see that happening, and if that's right, then the difference > sounds like it's related to buffered IO. Err, I see we actually default to direct when we open the file. You'd have to change that through configfs to use buffered, which I assume you're not doing. My mistake. _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme