Date: Thu, 21 Jan 2010 21:58:07 +0200 From: David Naylor <naylor.b.david@gmail.com> To: Andriy Gapon <avg@icyb.net.ua> Cc: freebsd-current@freebsd.org Subject: Re: stacked unionfs freeze and crash FreeBSD Message-ID: <201001212158.13250.naylor.b.david@gmail.com> In-Reply-To: <4B58953F.10404@icyb.net.ua> References: <201001201543.15818.naylor.b.david@gmail.com> <201001211952.20202.naylor.b.david@gmail.com> <4B58953F.10404@icyb.net.ua>
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[-- Attachment #1 --] On Thursday 21 January 2010 19:56:15 Andriy Gapon wrote: > on 21/01/2010 19:52 David Naylor said the following: > > On Wednesday 20 January 2010 19:16:59 Andriy Gapon wrote: > >> Double-fault could indicate stack overflow. > > > > Thanks, I bumped KSTACK_PAGES to 32 (just to be on the safe side) and it > > is working fairly well now. Only crash I have had since was related to > > tmpfs. So far I have successfully build a port with 59 stacked unionfs (1 > > rw, 58 ro). > > Good that you found a workaround, bad that there is no better way to handle > this overflow. Or, is there? What would make it easier is having kern.kstack_pages tunable (and having the appropriate changes to use that variable). I do not know the internals of the kernel but is it possible for unionfs (assuming it runs in its own thread) to specify a stack size big enough?. It might even be possible to extend unionfs to mount multiple directories onto another, at once (thus eliminating the need for multiple mounts). And probably a measurable performance increase? P.S. Twice I have had processes freeze, these were restricted to directories affected by unionfs mounts. [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.13 (FreeBSD) iEYEABECAAYFAktYsdUACgkQUaaFgP9pFrJ8EgCffURcPPOMn2X/PXngfsWxAMJD n9QAn0NS9hY4fF8y1Wi6Xy85EEd8DTAi =jLmX -----END PGP SIGNATURE-----help
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