From mboxrd@z Thu Jan 1 00:00:00 1970 From: robin.murphy@arm.com (Robin Murphy) Date: Mon, 26 Jun 2017 13:31:35 +0100 Subject: [PATCH v2 0/8] io-pgtable lock removal In-Reply-To: <9bbf18c7-34ba-6e94-53bd-3f75059c1bb2@huawei.com> References: <61b7b953-5bf4-eb45-c3e8-b4491e8fdca7@huawei.com> <9bbf18c7-34ba-6e94-53bd-3f75059c1bb2@huawei.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 26/06/17 12:35, John Garry wrote: > On 23/06/2017 10:58, Robin Murphy wrote: >> On 23/06/17 09:47, John Garry wrote: >>> On 22/06/2017 16:53, Robin Murphy wrote: >>>> The feedback has been promising, so v2 is just a final update to cover >>>> a handful of memory ordering and cosmetic tweaks that came up when Will >>>> and I went through this offline. >>>> >>>> Thanks, >>>> Robin. >>> >>> Hi Robin, >>> >>> Is it worth us retesting this patchset? >>> >>> If yes, as for a branch (for convenience), does this one now match v2: >>> git://linux-arm.org/linux-rm iommu/pgtable >>> >>> I saw it was rewritten recently. >> >> Indeed, I pushed the branch out before posting. Functionally it ought to >> be identical to v1, so this was more just a heads-up - feel free to >> double-check I've not broken anything, but I wouldn't say you need to >> throw the full test lab at it again. >> > > I saw Will has already sent the pull request. But, FWIW, we are seeing > roughly the same performance as v1 patchset. For PCI NIC, Zhou again > found performance drop goes from ~15->8% with SMMU enabled, and for > integrated storage controller [platform device], we still see a drop of > about 50%, depending on datarates (Leizhen has been working on fixing > this). Thanks for confirming. Following Joerg's suggestion that the storage workloads may still depend on rbtree performance - it had slipped my mind that even with small block sizes those could well be grouped into scatterlists large enough to trigger a >64-page IOVA allocation - I've taken the liberty of cooking up a simplified version of Leizhen's rbtree optimisation series in the iommu/iova branch of my tree. I'll follow up on that after the merge window, but if anyone wants to play with it in the meantime feel free. Robin.