Date: Thu, 21 Apr 2022 08:33:10 +0200 From: Alexander Leidinger <Alexander@leidinger.net> To: Doug Ambrisko <ambrisko@ambrisko.com> Cc: freebsd-current@freebsd.org Subject: Re: nullfs and ZFS issues Message-ID: <20220421083310.Horde.r7YT8777_AvGU_6GO1cC90G@webmail.leidinger.net> In-Reply-To: <YmAy0ZNZv9Cqs7X%2B@ambrisko.com> References: <Yl31Frx6HyLVl4tE@ambrisko.com> <20220420113944.Horde.5qBL80-ikDLIWDIFVJ4VgzX@webmail.leidinger.net> <YmAy0ZNZv9Cqs7X%2B@ambrisko.com>
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This message is in MIME format and has been PGP signed. --=_ynM4CAvCMj8TmUI2uVA8vHP Content-Type: multipart/mixed; boundary="=_NGnP2w2ySILE7xRtSYzRIXc" This message is in MIME format. --=_NGnP2w2ySILE7xRtSYzRIXc Content-Type: text/plain; charset=utf-8; format=flowed; DelSp=Yes Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Quoting Doug Ambrisko <ambrisko@ambrisko.com> (from Wed, 20 Apr 2022=20=20 09:20:33=20-0700): > On Wed, Apr 20, 2022 at 11:39:44AM +0200, Alexander Leidinger wrote: > | Quoting Doug Ambrisko <ambrisko@ambrisko.com> (from Mon, 18 Apr 2022 > | 16:32:38 -0700): > | > | > With nullfs, nocache and settings max vnodes to a low number I can > | > | Where is nocache documented? I don't see it in mount_nullfs(8), > | mount(8) or nullfs(5). > > I didn't find it but it is in: > src/sys/fs/nullfs/null_vfsops.c: if (vfs_getopt(mp->mnt_optnew,=20=20 >=20"nocache", NULL, NULL) =3D=3D 0 || > > Also some file systems disable it via MNTK_NULL_NOCACHE Does the attached diff look ok? > | I tried a nullfs mount with nocache and it doesn't show up in the > | output of "mount". > > Yep, I saw that as well. I could tell by dropping into ddb and then > do a show mount on the FS and look at the count. That is why I added > the vnode count to mount -v so I could see the usage without dropping > into ddb. I tried nocache on a system with a lot of jails which use nullfs,=20=20 which=20showed very slow behavior in the daily periodic runs (12h runs=20= =20 in=20the night after boot, 24h or more in subsequent nights). Now the=20=20 first=20nightly run after boot was finished after 4h. What is the benefit of not disabling the cache in nullfs? I would=20=20 expect=20zfs (or ufs) to cache the (meta)data anyway. Bye, Alexander. --=20 http://www.Leidinger.net=20Alexander@Leidinger.net: PGP 0x8F31830F9F2772BF http://www.FreeBSD.org netchild@FreeBSD.org : PGP 0x8F31830F9F2772BF --=_NGnP2w2ySILE7xRtSYzRIXc Content-Type: text/diff; charset=utf-8; name=mount.8.diff Content-Disposition: attachment; size=520; filename=mount.8.diff Content-Transfer-Encoding: quoted-printable diff --git a/sbin/mount/mount.8 b/sbin/mount/mount.8 index 2a877c04c07..823df63953d 100644 --- a/sbin/mount/mount.8 +++ b/sbin/mount/mount.8 @@ -28,7 +28,7 @@ .\" @(#)mount.8 8.8 (Berkeley) 6/16/94 .\" $FreeBSD$ .\" -.Dd March 17, 2022 +.Dd April 21, 2022 .Dt MOUNT 8 .Os .Sh NAME @@ -245,6 +245,9 @@ This file system should be skipped when is run with the .Fl a flag. +.It Cm nocache +Disable caching. +Some filesystems may not support this. .It Cm noclusterr Disable read clustering. .It Cm noclusterw --=_NGnP2w2ySILE7xRtSYzRIXc-- --=_ynM4CAvCMj8TmUI2uVA8vHP Content-Type: application/pgp-signature Content-Description: Digitale PGP-Signatur Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIzBAABCAAdFiEER9UlYXp1PSd08nWXEg2wmwP42IYFAmJg+qUACgkQEg2wmwP4 2Iai7xAAoBfUaimRkru9wrcadW8zCL7sUG2owGufjCZV5r9OE8XGUmMRwvL8RzZV Vo9nim8nXP6JQ3fSw2LguMNk+KEP0vQfkuB0xrvFRqldOkbsGmDU+T+isSHMW+z0 Pi1fsm6qtr5+p74ETGiMK03rwIfQThYUfsTdzIust8dD7yg+LyFSDK92+tG/BlKV YmWuA1KAMC7S6a4VCx1IpElnk9upnxP+fdOMXRaRY4i0T+g3u2iJ4FOSw4kpsSLd UpECjbTbwiRenMRHhOATnNfC6fxqNO7V5xkcUhMgOg6ZDk8g11AbxClroEldrSNm tGKEoiLDAO5n0jvnS3L71i+b94HA1bHAwraL6Kt8RFthYQ2zYXkyIGYbkelI2clJ +mV73+rSTqkKUqUkB9pmRHEm5prlIMWhDOktdRIGyTBW+ZzhS+TZrToJw6RRttXw EkdAfRl5ACmdsjS020AgswfMR6IHZpjcLYjwHSD7Br9KkX7/bPHCB53zqRX/jCP7 xIFC5LIPc7FzyFwmCg9gh3fLOsl/fstZ+ASGzR/hBMy5fAoPv63PNEChKIEt27eH paM67lMpH2+uatLQl0Rix+X6Xvnt1IfZpdFEeLtvKSrK+TZGYAXQ/xuowmzFqMDp PPa3D/1i7hXU+dnIU/MXL75iWyADM0A4/aGq5op/3SzQxZg2Ocg= =KCG4 -----END PGP SIGNATURE----- --=_ynM4CAvCMj8TmUI2uVA8vHP--
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