zfs discuss - Sep 2007 - ZFS ARC & DNLC Limitation

Hello All,

Awhile back (Feb ''07) when we noticed ZFS was hogging all the memory
on the system, y''all were kind enough to help us use the arc_max
tunable to attempt to limit that usage to a hard value. Unfortunately,
at the time a sticky problem was that the hard limit did not include
DNLC entries generated by ZFS.

I''ve been watching the list since then and trying to watch the Nevada
commits. I haven''t noticed that anything has been committed back so
that arc_max truly enforces the max amount of memory ZFS is allowed to
consume (including DNLC entries). Has this been corrected and I just
missed it? Thank you in advance for you any help.

Best Regards,
Jason

Hi Jason, This should have helped.

	6542676 ARC needs to track meta-data memory overhead

Some of the lines to arc.c:

1551          1.36 	if (arc_meta_used >= arc_meta_limit) {
1552               		/*
1553               		 * We are exceeding our meta-data cache limit.
1554               		 * Purge some DNLC entries to release holds on meta-data.
1555               		 */
1556               		dnlc_reduce_cache((void
*)(uintptr_t)arc_reduce_dnlc_percent);
1557               	}

-r



Jason J. W. Williams writes:
 > Hello All,
 > 
 > Awhile back (Feb ''07) when we noticed ZFS was hogging all the
memory
 > on the system, y''all were kind enough to help us use the arc_max
 > tunable to attempt to limit that usage to a hard value. Unfortunately,
 > at the time a sticky problem was that the hard limit did not include
 > DNLC entries generated by ZFS.
 > 
 > I''ve been watching the list since then and trying to watch the
Nevada
 > commits. I haven''t noticed that anything has been committed back
so
 > that arc_max truly enforces the max amount of memory ZFS is allowed to
 > consume (including DNLC entries). Has this been corrected and I just
 > missed it? Thank you in advance for you any help.
 > 
 > Best Regards,
 > Jason
 > _______________________________________________
 > zfs-discuss mailing list
 > zfs-discuss at opensolaris.org
 > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss