Date: Wed, 10 Mar 2010 15:05:14 +0100 From: Rafal Jaworowski <raj@semihalf.com> To: Bernd Walter <ticso@cicely7.cicely.de> Cc: Mark Tinguely <tinguely@casselton.net>, freebsd-arm@freebsd.org Subject: Re: Performance of SheevaPlug on 8-stable Message-ID: <0C313497-FA0C-4E93-A117-F73E4778C7FE@semihalf.com> In-Reply-To: <4B97A568.5080101@semihalf.com> References: <201003072125.o27LPfFb000968@casselton.net> <4B97A568.5080101@semihalf.com>
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On 2010-03-10, at 14:58, Grzegorz Bernacki wrote: >> There are a few data dangling allocations that I would like to see >> closed from the multiple kernel allocation fix. *IN THEORY, IF* a = page >> is allocated via the arm_nocache (DMA COHERENT) or a sendfile, then >> it is never marked as unallocated. *IN THEORY*, if that page is used >> again, then we could falsely believe that page is being shared and >> we turn off the cache, eventhough it is not shared. >> http://www.casselton.net/~tinguely/arm_pmap_unmanaged.diff >> * Disclaimer: I am not sure if DMA COHERENT nor sendfiles are used in >> the Sheeva implementation. This is a theoritical observation of a = side >> effect of the multiple kernel mapping patch that we did just before >> FreeBSD 8-release. >=20 > I instrumented code with KTRs and your theory is correct. Kernel reuse = page > which was previouly mapped via arm_nocache. Your patch should be = applied > to -current. Bernd, Could you confirm this also fixes the issues for you on the RM9200 = machine? If so, I'll go on and commit the changes. Rafal
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