From mboxrd@z Thu Jan 1 00:00:00 1970 From: axboe@kernel.dk (Jens Axboe) Date: Thu, 17 May 2018 08:16:17 -0600 Subject: [PATCH] nvme: remove cq check after submission In-Reply-To: <20180517065049.GA30079@infradead.org> References: <20180516212010.GC20223@localhost.localdomain> <20180517065049.GA30079@infradead.org> Message-ID: On 5/17/18 12:50 AM, Christoph Hellwig wrote: > On Wed, May 16, 2018@03:20:10PM -0600, Keith Busch wrote: >> On Wed, May 16, 2018@01:58:08PM -0600, Jens Axboe wrote: >>> We always check the completion queue after submitting, but in my testing >>> this isn't a win even on DRAM/xpoint devices. In some cases it's >>> actually worse. Kill it. >> >> Right, this was on my todo list. Agreed it's not helping anything. >> Applied to nvme-4.18. > > While I agree in general didn't we have a case where this caused a > regression last time it came up? Not that I'd complain if it goes > away.. Not that I'm aware of. I've been running with this patch for quite a while, while doing some work on polling. > But more importantly we could split q_lock into a sq_lock and cq_lock > now, which might bring real benefits. Exactly, especially on queue starved setups. -- Jens Axboe