Date: Wed, 15 Jun 2016 14:05:16 +0200 From: Fabian Keil <freebsd-listen@fabiankeil.de> To: freebsd-hackers@freebsd.org Subject: vnlru_proc() draining unrelated uma zones Message-ID: <20160615140516.3cba6001@fabiankeil.de>
next in thread | raw e-mail | index | archive | help
--Sig_/ERk0lYNaHqqLuRujEm_vn6k
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: quoted-printable
While looking into two uma-related issues[0] I noticed that
vnlru_proc() is calling uma_reclaim() even though the intention
seems to be to merely drain the vnode-related zones.
According to uma.h, uma_reclaim() "should only be called by
the page out daemon", presumably because of the overhead
and side-effects.
I've been using this patch for a couple of weeks and didn't
notice any regressions:
diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index 2767826..2c65ce1 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -1107,8 +1107,10 @@ vnlru_proc(void)
vfs_unbusy(mp);
}
mtx_unlock(&mountlist_mtx);
- if (onumvnodes > desiredvnodes && numvnodes <=3D desiredvno=
des)
- uma_reclaim();
+ if (onumvnodes > desiredvnodes && numvnodes <=3D desiredvno=
des) {
+ zone_drain(vnode_zone);
+ zone_drain(vnodepoll_zone);
+ }
if (done =3D=3D 0) {
if (force =3D=3D 0 || force =3D=3D 1) {
force =3D 2;
It also didn't seem to noticeable affect the issues I was investigating
(the code is rarely executed on my systems), but calling uma_reclaim()
still seems strange to me.
Am I missing something?
Fabian
[0]
"Prevent deadlocks when paging on GELI-encrypted devices":
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D209759
"[...] connections time out/ssh results in 'broken pipe'":
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D209680
--Sig_/ERk0lYNaHqqLuRujEm_vn6k
Content-Type: application/pgp-signature
Content-Description: OpenPGP digital signature
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2
iEYEARECAAYFAldhRH0ACgkQBYqIVf93VJ16qgCfbyuMri2/5q+1vll5GYNcwJJZ
GCgAnjro8MsibfgqXax/35n3mdg8yDni
=NuTq
-----END PGP SIGNATURE-----
--Sig_/ERk0lYNaHqqLuRujEm_vn6k--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20160615140516.3cba6001>