From: Jan Beulich <email@example.com> To: Hongyan Xia <firstname.lastname@example.org> Cc: Stefano Stabellini <email@example.com>, Julien Grall <firstname.lastname@example.org>, Wei Liu <email@example.com>, Andrew Cooper <firstname.lastname@example.org>, Ian Jackson <email@example.com>, George Dunlap <firstname.lastname@example.org>, email@example.com Subject: Re: [Xen-devel] [PATCH] Revert "domctl: improve locking during domain destruction" Date: Tue, 24 Mar 2020 17:13:45 +0100 [thread overview] Message-ID: <firstname.lastname@example.org> (raw) In-Reply-To: <email@example.com> On 24.03.2020 16:21, Hongyan Xia wrote: > From: Hongyan Xia <firstname.lastname@example.org> > > Unfortunately, even though that commit dropped the domctl lock and > allowed other domctl to continue, it created severe lock contention > within domain destructions themselves. Multiple domain destructions in > parallel now spin for the global heap lock when freeing memory and could > spend a long time before the next hypercall continuation. I'm not at all happy to see this reverted; instead I was hoping that we could drop the domctl lock in further cases. If a lack of continuations is the problem, did you try forcing them to occur more frequently? > In contrast, > after dropping that commit, parallel domain destructions will just fail > to take the domctl lock, creating a hypercall continuation and backing > off immediately, allowing the thread that holds the lock to destroy a > domain much more quickly and allowing backed-off threads to process > events and irqs. > > On a 144-core server with 4TiB of memory, destroying 32 guests (each > with 4 vcpus and 122GiB memory) simultaneously takes: > > before the revert: 29 minutes > after the revert: 6 minutes This wants comparing against numbers demonstrating the bad effects of the global domctl lock. Iirc they were quite a bit higher than 6 min, perhaps depending on guest properties. Jan
next prev parent reply other threads:[~2020-03-24 16:14 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-03-24 15:21 Hongyan Xia 2020-03-24 16:13 ` Jan Beulich [this message] 2020-03-24 18:39 ` Julien Grall 2020-03-25 7:11 ` Jan Beulich 2020-03-26 14:39 ` Hongyan Xia 2020-03-26 16:55 ` Jim Fehlig 2020-03-31 10:31 ` Julien Grall 2020-03-24 18:40 ` [Xen-devel] " Julien Grall
Reply instructions: You may reply publicly 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 \ --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 \ --subject='Re: [Xen-devel] [PATCH] Revert "domctl: improve locking during domain destruction"' \ /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
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).