Date: Thu, 27 May 2004 12:12:05 -0400 From: "lost inferno" <bjohns123@hotmail.com> To: tinguely@casselton.net, freebsd-hackers@freebsd.org Subject: Re: KVA space problems? Message-ID: <BAY8-F363CrJRxKZMqA000449b8@hotmail.com>
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You know, of all the responses i got... it seems yours is the most technical and unbiased of the lot. Thank you for that. I wish everyone here wasnt so jaded in their own oppinion. as for the problem... From what you wrote, the best idea would be to keep the mbuf limits ether at the defaults or lower than the kva space? and or to run a 5x or later release. The reasoning for this is from an experiance i had a few months ago with a dual xeon with HT sporaticly locking up under load. I had hoped to move an old ( Free 4.8 ) onto the same hardware without hopfully having to reinstall. >From: Mark Tinguely <tinguely@casselton.net> >To: bjohns123@msn.com, freebsd-hackers@freebsd.org >Subject: Re: KVA space problems? >Date: Wed, 26 May 2004 15:47:41 -0500 (CDT) > >This has been seen before and there is at least one open problem report >that the kernel malloc() unexpectantly returns NULL in WAITOK situations. > > http://www.freebsd.org/cgi/query-pr.cgi?pr=i386/53382 > > --- >I think malloc returns before your patch, namely around line 199: > > va = (caddr_t) kmem_malloc(kmem_map, (vm_size_t)ctob(npg), flags >); > if (va == NULL) { > splx(s); > return ((void *) NULL); > } > >Although, I agree that the kernel malloc() should not do this, if KVM >is depleted or fragmented to this point, I suspect your changes of simply >retrying again will cause an infinite loop in malloc(). > >If malloc() sleeps waiting for KVM to be freed, my guess this will lead to >the processes to hang for a long time if not forever. > >I think this because people are bumping the MBUFs numbers up and not >changing the KVM size, once the KVM is depleted/fragmented it shouldn't >come down for a long time. > --- >The pre 5.x VM assumes KVM will not be depleted. contigmalloc() used to >leak >physical pages if the KVM got depleted. I was told "the system will panic >soon anyway, why put them back". > >--Mark Tinguely >_______________________________________________ >freebsd-hackers@freebsd.org mailing list >http://lists.freebsd.org/mailman/listinfo/freebsd-hackers >To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org" _________________________________________________________________ Get 200+ ad-free, high-fidelity stations and LIVE Major League Baseball Gameday Audio! http://radio.msn.click-url.com/go/onm00200491ave/direct/01/
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