Date: Mon, 21 Aug 2023 11:53:48 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Alexander Leidinger <Alexander@leidinger.net> Cc: Mateusz Guzik <mjguzik@gmail.com>, current@freebsd.org Subject: Re: Speed improvements in ZFS Message-ID: <ZOMmHF0RiVyroUk8@kib.kiev.ua> In-Reply-To: <58ac6211235c52d744666e8ae2ec7568@Leidinger.net> References: <CAGudoHEP8TrSzz0TL-PsOx0WNc7z3042wJk-jhhVwhTyJ0VEQQ@mail.gmail.com> <88e837aeb5a65c1f001de2077fb7bcbd@Leidinger.net> <4d60bd12b482e020fd4b186a9ec1a250@Leidinger.net> <CAGudoHE7RPcHpQEqKbzRM8cJcYKue17=iPVv8iOfZq03h22tTA@mail.gmail.com> <73f7c9d3db8f117deb077fb17b1e352a@Leidinger.net> <CAGudoHGPw0Dmnv6ont8JGyLsT7qv%2BQqAFZO3tKOpNo3eN%2BJgLQ@mail.gmail.com> <58493b568dbe9fb52cc55de86e01f5e2@Leidinger.net> <CAGudoHEyZh1DU=j_6mOfB3tSKhC-pNokPgONDbf4oF3D3A5=jg@mail.gmail.com> <ZOKC3-6uyPUO8qNY@kib.kiev.ua> <58ac6211235c52d744666e8ae2ec7568@Leidinger.net>
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On Mon, Aug 21, 2023 at 08:19:28AM +0200, Alexander Leidinger wrote: > Am 2023-08-20 23:17, schrieb Konstantin Belousov: > > On Sun, Aug 20, 2023 at 11:07:08PM +0200, Mateusz Guzik wrote: > > > On 8/20/23, Alexander Leidinger <Alexander@leidinger.net> wrote: > > > > Am 2023-08-20 22:02, schrieb Mateusz Guzik: > > > >> On 8/20/23, Alexander Leidinger <Alexander@leidinger.net> wrote: > > > >>> Am 2023-08-20 19:10, schrieb Mateusz Guzik: > > > >>>> On 8/18/23, Alexander Leidinger <Alexander@leidinger.net> wrote: > > > >>> > > > >>>>> I have a 51MB text file, compressed to about 1MB. Are you interested > > > >>>>> to > > > >>>>> get it? > > > >>>>> > > > >>>> > > > >>>> Your problem is not the vnode limit, but nullfs. > > > >>>> > > > >>>> https://people.freebsd.org/~mjg/netchild-periodic-find.svg > > > >>> > > > >>> 122 nullfs mounts on this system. And every jail I setup has several > > > >>> null mounts. One basesystem mounted into every jail, and then shared > > > >>> ports (packages/distfiles/ccache) across all of them. > > > >>> > > > >>>> First, some of the contention is notorious VI_LOCK in order to do > > > >>>> anything. > > > >>>> > > > >>>> But more importantly the mind-boggling off-cpu time comes from > > > >>>> exclusive locking which should not be there to begin with -- as in > > > >>>> that xlock in stat should be a slock. > > > >>>> > > > >>>> Maybe I'm going to look into it later. > > > >>> > > > >>> That would be fantastic. > > > >>> > > > >> > > > >> I did a quick test, things are shared locked as expected. > > > >> > > > >> However, I found the following: > > > >> if ((xmp->nullm_flags & NULLM_CACHE) != 0) { > > > >> mp->mnt_kern_flag |= > > > >> lowerrootvp->v_mount->mnt_kern_flag & > > > >> (MNTK_SHARED_WRITES | MNTK_LOOKUP_SHARED | > > > >> MNTK_EXTENDED_SHARED); > > > >> } > > > >> > > > >> are you using the "nocache" option? it has a side effect of xlocking > > > > > > > > I use noatime, noexec, nosuid, nfsv4acls. I do NOT use nocache. > > > > > > > > > > If you don't have "nocache" on null mounts, then I don't see how this > > > could happen. > > > > There is also MNTK_NULL_NOCACHE on lower fs, which is currently set for > > fuse and nfs at least. > > 11 of those 122 nullfs mounts are ZFS datasets which are also NFS exported. > 6 of those nullfs mounts are also exported via Samba. The NFS exports > shouldn't be needed anymore, I will remove them. By nfs I meant nfs client, not nfs exports. > > Shouldn't this implicit nocache propagate to the mount of the upper fs to > give the user feedback about the effective state? > > Bye, > Alexander. > > -- > http://www.Leidinger.net Alexander@Leidinger.net: PGP 0x8F31830F9F2772BF > http://www.FreeBSD.org netchild@FreeBSD.org : PGP 0x8F31830F9F2772BF
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