From: Jan Beulich <firstname.lastname@example.org> To: Julien Grall <email@example.com> Cc: Hongyan Xia <firstname.lastname@example.org>, Charles Arnold <CARNOLD@suse.com>, Stefano Stabellini <email@example.com>, Wei Liu <firstname.lastname@example.org>, Andrew Cooper <email@example.com>, Ian Jackson <firstname.lastname@example.org>, George Dunlap <email@example.com>, Jim Fehlig <JFEHLIG@suse.com>, firstname.lastname@example.org Subject: Re: [Xen-devel] [PATCH] Revert "domctl: improve locking during domain destruction" Date: Wed, 25 Mar 2020 08:11:53 +0100 [thread overview] Message-ID: <email@example.com> (raw) In-Reply-To: <firstname.lastname@example.org> On 24.03.2020 19:39, Julien Grall wrote: > On 24/03/2020 16:13, Jan Beulich wrote: >> On 24.03.2020 16:21, Hongyan Xia wrote: >>> From: Hongyan Xia <email@example.com> >>> 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. > > Your original commit message doesn't contain any clue in which > cases the domctl lock was an issue. So please provide information > on the setups you think it will make it worse. I did never observe the issue myself - let's see whether one of the SUSE people possibly involved in this back then recall (or have further pointers; Jim, Charles?), or whether any of the (partly former) Citrix folks do. My vague recollection is that the issue was the tool stack as a whole stalling for far too long in particular when destroying very large guests. One important aspect not discussed in the commit message at all is that holding the domctl lock block basically _all_ tool stack operations (including e.g. creation of new guests), whereas the new issue attempted to be addressed is limited to just domain cleanup. Jan
next prev parent reply other threads:[~2020-03-25 7:12 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 2020-03-24 18:39 ` Julien Grall 2020-03-25 7:11 ` Jan Beulich [this message] 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 \ --firstname.lastname@example.org \ --email@example.com \ --cc=CARNOLD@suse.com \ --cc=JFEHLIG@suse.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: [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).