Date: Sat, 23 Apr 2022 19:20:24 -0700 From: Pete Wright <pete@nomadlogic.org> To: Mark Millard <marklmi@yahoo.com> Cc: freebsd-current <freebsd-current@freebsd.org> Subject: Re: Chasing OOM Issues - good sysctl metrics to use? Message-ID: <f43d7276-3718-df89-cbf0-5c1ef3d67e77@nomadlogic.org> In-Reply-To: <DD98C932-A07F-4097-AE7F-D9CEF0BB6AEE@yahoo.com> References: <83A713B9-A973-4C97-ACD6-830DF6A50B76.ref@yahoo.com> <83A713B9-A973-4C97-ACD6-830DF6A50B76@yahoo.com> <a5b2e248-3298-80e3-4bb6-742c8431f064@nomadlogic.org> <94B2E2FD-2371-4FEA-8E01-F37103F63CC0@yahoo.com> <0fcb5a4a-5517-e57b-2b69-4f3b3b10589a@nomadlogic.org> <DD98C932-A07F-4097-AE7F-D9CEF0BB6AEE@yahoo.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On 4/23/22 12:31, Mark Millard wrote: > I think you may have taken my suggestion backwards . . . > > Unfortunately, vnode (file) based swap space should be *avoided* > and partitions are what should be used in order to avoid deadlocks: > > On 2017-Feb-13, at 7:20 PM, Konstantin Belousov <kostikbel at gmail.com> wrote > on the freebsd-arm list: > > QUOTE > swapfile write requires the write request to come through the filesystem > write path, which might require the filesystem to allocate more memory > and read some data. E.g. it is known that any ZFS write request > allocates memory, and that write request on large UFS file might require > allocating and reading an indirect block buffer to find the block number > of the written block, if the indirect block was not yet read. > > As result, swapfile swapping is more prone to the trivial and unavoidable > deadlocks where the pagedaemon thread, which produces free memory, needs > more free memory to make a progress. Swap write on the raw partition over > simple partitioning scheme directly over HBA are usually safe, while e.g. > zfs over geli over umass is the worst construction. > END QUOTE > > The developers handbook has a section debugging deadlocks that he > referenced in a response to another report (on freebsd-hackers). > > https://docs.freebsd.org/en/books/developers-handbook/kerneldebug/#kerneldebug-deadlocks d'oh - thanks for the correction! -pete -- Pete Wright pete@nomadlogic.org @nomadlogicLA
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?f43d7276-3718-df89-cbf0-5c1ef3d67e77>