On Tue, Mar 27 2018 at 4:55am -0400, yael.chemla@xxxxxxxxxxxx <yael.chemla@xxxxxxxxxxxx> wrote: > Hi Mike > I need to rewrite these patches according to issues you and Eric Biggers mentioned. > please drop this v1 patch. They've been dropped. BUT please do note that the patches I pushed to linux-dm.git were rebased ontop of the 'check_at_most_once' patch. I never did get an answer about how the sg array is free'd in certain error paths (see "FIXME:" in the 2nd patch). Also, I fixed some issues I saw in error paths, and lots of formatting. I'll be pretty frustrated if you submit v2 that is blind to the kinds of changes I made. I'll send you a private copy of the patches just so you have them for your reference. Thanks, Mike > -----Original Message----- > From: Mike Snitzer <snitzer@xxxxxxxxxx> > Sent: Tuesday, 27 March 2018 4:07 > To: Yael Chemla <yael.chemla@xxxxxxxxxxxx> > Cc: Alasdair Kergon <agk@xxxxxxxxxx>; dm-devel@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; ofir.drang@xxxxxxxxx; Yael Chemla <yael.chemla@xxxxxxx> > Subject: Re: [PATCH 2/2] md: dm-verity: allow parallel processing of bio blocks > > On Sun, Mar 25 2018 at 2:41pm -0400, > Yael Chemla <yael.chemla@xxxxxxxxxxxx> wrote: > > > Allow parallel processing of bio blocks by moving to async. > > completion handling. This allows for better resource utilization of > > both HW and software based hash tfm and therefore better performance > > in many cases, depending on the specific tfm in use. > > > > Tested on ARM32 (zynq board) and ARM64 (Juno board). > > Time of cat command was measured on a filesystem with various file sizes. > > 12% performance improvement when HW based hash was used (ccree driver). > > SW based hash showed less than 1% improvement. > > CPU utilization when HW based hash was used presented 10% less > > context switch, 4% less cycles and 7% less instructions. No > > difference in CPU utilization noticed with SW based hash. > > > > Signed-off-by: Yael Chemla <yael.chemla@xxxxxxxxxxxx> > > This one had various issues. I've fixed most of what I saw and staged in linux-next (purely for build test coverage purposes). I may drop this patch if others disagree with it (or my sg deallocation in the error path question isn't answered). > > I've staged the changes here (and in linux-next via 'for-next'): > https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git/log/?h=dm-4.17 > > I switched all the new GFP_KERNEL uses to GFP_NOIO. The fact that you're doing allocations at all (per IO) is bad enough. Using GFP_KERNEL is a serious liability (risk of deadlock if dm-verity were to be used for something like.. swap.. weird setup but possible). > > But the gfp flags aside, the need for additional memory and the expectation of scalable async parallel IO is potentially at odds with changes like this (that I just staged, and had to rebase your 2 patches ontop of): > https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=dm-4.17&id=a89f6a2cfec86fba7a115642ff082cb4e9450ea6 > > So I'm particulalry interested to hear from google folks to understand if they are OK with your proposed verity async crypto API use. > > Mike > -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
