You can try it, but that isn't a fix, that is a way to make the flushing run all the time at full rate. If I remember correctly, old behaviour was that the flushing would happen at innodb_io_capacity rate, and above the hwm, it would kick into innodb_io_capacity_max rate. Or something along those lines. On 10.5+ you get only two speeds, 0 and whatever your disks can handle (which can also starve other I/O) Whatever the "improvement" intended was, the outcome is a substantial downgrade.
On Wed, Jul 27, 2022 at 3:36 PM Cédric Counotte <cedric.couno...@1check.com> wrote: > > Reading this: https://jira.mariadb.org/browse/MDEV-27295 > > It's quite unclear when it is fixed or reverted. > > That said I read that the following setting might fix it: > SET GLOBAL innodb_max_dirty_pages_pct_lwm=0.001; > > Is that correct and should I try that and see if that helps? > > > -----Message d'origine----- > De : Gordan Bobic <gordan.bo...@gmail.com> > Envoyé : mercredi 27 juillet 2022 14:29 > À : Marko Mäkelä <marko.mak...@mariadb.com> > Cc : Cédric Counotte <cedric.couno...@1check.com>; Mailing-List mariadb > <maria-discuss@lists.launchpad.net> > Objet : Re: [Maria-discuss] MariaDB server horribly slow on start > > On Wed, Jul 27, 2022 at 3:08 PM Marko Mäkelä <marko.mak...@mariadb.com> wrote: > > > > On Wed, Jul 27, 2022 at 2:48 PM Gordan Bobic <gordan.bo...@gmail.com> wrote: > > > > > > There is no supported downgrade path other than logical dump+restore. > > > There are also no packages built for distros where the major version is > > > older than what ships with the distro. > > > > > > Since your queries seem to end up stuck in commit stage, it could be > > > related to redo log flushing, which behaves very erratically on 10.5+. If > > > it leaves the log to fill up to 90% and the state transfer hits, it could > > > be that with the checkpoint age already high, there just isn't enough > > > headroom to avoid a massive stall. Purely guessing here without any > > > telemetry. > > > > I think that you may refer to InnoDB page flushing. There was some > > misunderstanding around that, and indeed some partly unintended or > > uninformed changes in behaviour (in 10.5.7 and 10.5.8) that were > > reverted later. It could be useful to read > > https://jira.mariadb.org/browse/MDEV-27295. > > What version was it reverted in? > I am still seeing the errant redo log flushing behaviour in 10.5.15. > It looks like no flushing happens until the hwm is reached at about 85% full. > It then tries to commit everything down to the lwm. And inbetween it doesn't > do anything, even while everything is idle and it should be running down the _______________________________________________ Mailing list: https://launchpad.net/~maria-discuss Post to : maria-discuss@lists.launchpad.net Unsubscribe : https://launchpad.net/~maria-discuss More help : https://help.launchpad.net/ListHelp
