From: Marc Zyngier <email@example.com> To: John Garry <firstname.lastname@example.org> Cc: Ming Lei <email@example.com>, <firstname.lastname@example.org>, "chenxiang (M)" <email@example.com>, <firstname.lastname@example.org>, <email@example.com>, <firstname.lastname@example.org>, <email@example.com>, <firstname.lastname@example.org>, <email@example.com>, <firstname.lastname@example.org>, <email@example.com> Subject: Re: [PATCH RFC 1/1] genirq: Make threaded handler use irq affinity for managed interrupt Date: Mon, 23 Dec 2019 10:47:07 +0000 Message-ID: <firstname.lastname@example.org> (raw) In-Reply-To: <email@example.com> On 2019-12-23 10:26, John Garry wrote: >>>> > I've also managed to trigger some of them now that I have access >>>> to >>>> > a decent box with nvme storage. >>>> >>>> I only have 2x NVMe SSDs when this occurs - I should not be >>>> hitting this... >>>> >>>> Out of curiosity, have you tried >>>> > with the SMMU disabled? I'm wondering whether we hit some >>>> livelock >>>> > condition on unmapping buffers... >>>> >>>> No, but I can give it a try. Doing that should lower the CPU >>>> usage, though, >>>> so maybe masks the issue - probably not. >>> >>> Lots of CPU lockup can is performance issue if there isn't obvious >>> bug. >>> >>> I am wondering if you may explain it a bit why enabling SMMU may >>> save >>> CPU a it? >> The other way around. mapping/unmapping IOVAs doesn't comes for >> free. >> I'm trying to find out whether the NVMe map/unmap patterns trigger >> something unexpected in the SMMU driver, but that's a very long >> shot. > > So I tested v5.5-rc3 with and without the SMMU enabled, and without > the SMMU enabled I don't get the lockup. OK, so my hunch wasn't completely off... At least we have something to look into. [...] > Obviously this is not conclusive, especially with such limited > testing - 5 minute runs each. The CPU load goes up when disabling the > SMMU, but that could be attributed to extra throughput (1183K -> > 1539K) loading. > > I do notice that since we complete the NVMe request in irq context, > we also do the DMA unmap, i.e. talk to the SMMU, in the same context, > which is less than ideal. It depends on how much overhead invalidating the TLB adds to the equation, but we should be able to do some tracing and find out. > I need to finish for the Christmas break today, so can't check this > much further ATM. No worries. May I suggest creating a new thread in the new year, maybe involving Robin and Will as well? Thanks, M. -- Jazz is not dead. It just smells funny...
next prev parent reply index Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-12-06 14:35 [PATCH RFC 0/1] Threaded handler uses irq affinity for when the interrupt is managed John Garry 2019-12-06 14:35 ` [PATCH RFC 1/1] genirq: Make threaded handler use irq affinity for managed interrupt John Garry 2019-12-06 15:22 ` Marc Zyngier 2019-12-06 16:16 ` John Garry 2019-12-07 8:03 ` Ming Lei 2019-12-09 14:30 ` John Garry 2019-12-09 15:09 ` Hannes Reinecke 2019-12-09 15:17 ` Marc Zyngier 2019-12-09 15:25 ` Hannes Reinecke 2019-12-09 15:36 ` Marc Zyngier 2019-12-09 15:49 ` Qais Yousef 2019-12-09 15:55 ` Marc Zyngier 2019-12-10 1:43 ` Ming Lei 2019-12-10 9:45 ` John Garry 2019-12-10 10:06 ` Ming Lei 2019-12-10 10:28 ` Marc Zyngier 2019-12-10 10:59 ` John Garry 2019-12-10 11:36 ` Marc Zyngier 2019-12-10 12:05 ` John Garry 2019-12-10 18:32 ` Marc Zyngier 2019-12-11 9:41 ` John Garry 2019-12-13 10:07 ` John Garry 2019-12-13 10:31 ` Marc Zyngier 2019-12-13 12:08 ` John Garry 2019-12-14 10:59 ` Marc Zyngier 2019-12-11 17:09 ` John Garry 2019-12-12 22:38 ` Ming Lei 2019-12-13 11:12 ` John Garry 2019-12-13 13:18 ` Ming Lei 2019-12-13 15:43 ` John Garry 2019-12-13 17:12 ` Ming Lei 2019-12-13 17:50 ` John Garry 2019-12-14 13:56 ` Marc Zyngier 2019-12-16 10:47 ` John Garry 2019-12-16 11:40 ` Marc Zyngier 2019-12-16 14:17 ` John Garry 2019-12-16 18:00 ` Marc Zyngier 2019-12-16 18:50 ` John Garry 2019-12-20 11:30 ` John Garry 2019-12-20 14:43 ` Marc Zyngier 2019-12-20 15:38 ` John Garry 2019-12-20 16:16 ` Marc Zyngier 2019-12-20 23:31 ` Ming Lei 2019-12-23 9:07 ` Marc Zyngier 2019-12-23 10:26 ` John Garry 2019-12-23 10:47 ` Marc Zyngier [this message] 2019-12-23 11:35 ` John Garry 2019-12-24 1:59 ` Ming Lei 2019-12-24 11:20 ` Marc Zyngier 2019-12-25 0:48 ` Ming Lei 2020-01-02 10:35 ` John Garry 2020-01-03 0:46 ` Ming Lei 2020-01-03 10:41 ` John Garry 2020-01-03 11:29 ` Ming Lei 2020-01-03 11:50 ` John Garry 2020-01-04 12:03 ` Ming Lei
Reply instructions: You may reply publically to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
LKML Archive on lore.kernel.org Archives are clonable: git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git git clone --mirror https://lore.kernel.org/lkml/8 lkml/git/8.git # If you have public-inbox 1.1+ installed, you may # initialize and index your mirror using the following commands: public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \ firstname.lastname@example.org public-inbox-index lkml Example config snippet for mirrors Newsgroup available over NNTP: nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel AGPL code for this site: git clone https://public-inbox.org/public-inbox.git