Date: Sat, 29 Jan 2011 16:36:39 +0100 From: Martin Matuska <mm@FreeBSD.org> To: Artem Belevich <fbsdlist@src.cx> Cc: freebsd-fs <freebsd-fs@freebsd.org> Subject: Re: ZFS: clock_t overflow in l2arc_feed_thread Message-ID: <4D443407.7010604@FreeBSD.org> In-Reply-To: <AANLkTikciV_XHvrurytr0-r11W4u=_p5bRi-xfX3S%2BQm@mail.gmail.com> References: <AANLkTikciV_XHvrurytr0-r11W4u=_p5bRi-xfX3S%2BQm@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
This is a multi-part message in MIME format. --------------010203040206090602080803 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit I agree to you that we have different types and this may be an issue but I disagree to your patch. clock_t is not signed (int64_t) and this can be done in a much easier (and cleaner way) without touching the code, see attached patch. Dňa 29.01.2011 11:30, Artem Belevich wrote / napísal(a) > Hi, > > I'm using ZFS v15 on RELENG_8/amd64 box. Some time back I've noticed > that after a while ZFS starts to consume 100% of CPU time on one of > the cores. After a bit of digging it appears that the problem is due > to an integer overflow. > > On amd64 (as wel as most other FreeBSD platforms) clock_t is a signed > 32-bit integer. On OpenSolaris clock_t is long. > > In compat/opensolaris/sys/time.h LBOLT is defined as > #define LBOLT ((gethrtime() * hz) / NANOSEC) > > With HZ=1000 LBOLT overflows clock_t variables when uptime reaches > ~24days. This affects l2arc_write_interval() which calculates the time > when L2ARC feed thread should be woken up. The end result is that for > the next 24 days l2arc_feed_thread no longer sleeps as long as it > should have. > > Changing clock_t to a larger type globally looks somewhat risky to me. > It's probably easier to change those few places in ZFS code that use > clock_t to uint64_t instead. > > In case someone is interested, I've posted my patch here: > http://pastebin.com/Q2T3x2AB > > --Artem > _______________________________________________ > freebsd-fs@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-fs > To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org" --------------010203040206090602080803 Content-Type: text/x-patch; name="opensolaris_types.patch" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="opensolaris_types.patch" --- sys/cddl/compat/opensolaris/sys/types.h.orig 2011-01-29 16:25:48.857709276 +0100 +++ sys/cddl/compat/opensolaris/sys/types.h 2011-01-29 16:26:03.219594069 +0100 @@ -29,6 +29,9 @@ #ifndef _OPENSOLARIS_SYS_TYPES_H_ #define _OPENSOLARIS_SYS_TYPES_H_ +typedef long clock_t; +#define _CLOCK_T_DECLARED + /* * This is a bag of dirty hacks to keep things compiling. */ --------------010203040206090602080803--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?4D443407.7010604>