Date: Mon, 21 Aug 2023 00:17:19 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Mateusz Guzik <mjguzik@gmail.com> Cc: Alexander Leidinger <Alexander@leidinger.net>, current@freebsd.org Subject: Re: Speed improvements in ZFS Message-ID: <ZOKC3-6uyPUO8qNY@kib.kiev.ua> In-Reply-To: <CAGudoHEyZh1DU=j_6mOfB3tSKhC-pNokPgONDbf4oF3D3A5=jg@mail.gmail.com> References: <CAGudoHG5Fgg4184SsXhzqYRR7VPaBXZoirGvyRyJX5ihX5YG-A@mail.gmail.com> <ed1f82dd26d3cc9ec9cc16505109ec40@Leidinger.net> <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>
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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.
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