Date: Mon, 27 Mar 2006 22:54:40 +0900 From: Kazuaki Oda <kaakun@highway.ne.jp> To: Gabor MICSKO <gmicsko@szintezis.hu> Cc: freebsd-net@freebsd.org, freebsd-current@freebsd.org Subject: Re: requests for mbufs denied Message-ID: <4427EEA0.3040603@highway.ne.jp> In-Reply-To: <1143058963.6826.11.camel@alderaan.trey.hu> References: <1143058963.6826.11.camel@alderaan.trey.hu>
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Gabor MICSKO wrote: > Hi! > > I have a relative high traffic server, running Apache, MySQL and Drupal. > With FreeBSD 6.0 and 6.1-PRERELEASE i got some distressing "netstat -m" > outputs. > > Can anybody explain for me what does this message mean exactly? > > "16064849/9164254/9384500 requests for mbufs denied (mbufs/clusters/mbuf > +clusters)" > > And what can i do with this? > > Full "netstat -m" output: > > $ netstat -m > 445/695/1140 mbufs in use (current/cache/total) > 407/255/662/65536 mbuf clusters in use (current/cache/total/max) > 407/237 mbuf+clusters out of packet secondary zone in use > (current/cache) > 0/0/0/0 4k (page size) jumbo clusters in use (current/cache/total/max) > 0/0/0/0 9k jumbo clusters in use (current/cache/total/max) > 0/0/0/0 16k jumbo clusters in use (current/cache/total/max) > 925K/683K/1609K bytes allocated to network (current/cache/total) > 16064849/9164254/9384500 requests for mbufs denied (mbufs/clusters/mbuf > +clusters) > 0/0/0 requests for jumbo clusters denied (4k/9k/16k) > 33/964/6656 sfbufs in use (current/peak/max) > 0 requests for sfbufs denied > 0 requests for sfbufs delayed > 56067 requests for I/O initiated by sendfile > 5500 calls to protocol drain routines > > > Sorry for my bad english. > > Thank you! > > In my case, that happens when the number of free pages become less than vm.v_free_min. In such case, we drain cached buckets from zones (including mbuf zone) to the system to get more free pages, and disable bucket allocation. As the result, we cannot get a bucket when freeing a mbuf to the zone and just do internal free, counting up the number of allocation failure, i.e. the number of "requests for mbufs denied". I don't know whether this (as to counting up the number of failure in such case) is expected or not. -- Kazuaki Oda
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