Date: Fri, 06 Aug 2010 00:41:28 -0500 From: Alan Cox <alc@cs.rice.edu> To: "Jayachandran C." <c.jayachandran@gmail.com> Cc: "Jayachandran C." <jchandra@freebsd.org>, mips@freebsd.org Subject: Re: svn commit: r210846 - in head/sys/mips: include mips Message-ID: <4C5BA088.7060105@cs.rice.edu> In-Reply-To: <AANLkTi=vkG-cntJYYEdhO4AzOO91LB6n%2B45dUSxCMTp3@mail.gmail.com> References: <201008041412.o74ECAix092415@svn.freebsd.org> <4C5A569B.9090401@cs.rice.edu> <AANLkTinP7eMNm4yp6T2TTteSvthdgLJOj-ihHrQJ4T49@mail.gmail.com> <AANLkTi=vkG-cntJYYEdhO4AzOO91LB6n%2B45dUSxCMTp3@mail.gmail.com>
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On 08/05/2010 09:25, Jayachandran C. wrote: > On Thu, Aug 5, 2010 at 4:26 PM, Jayachandran C. > <c.jayachandran@gmail.com> wrote: > >> On Thu, Aug 5, 2010 at 11:43 AM, Alan Cox<alc@cs.rice.edu> wrote: >> >>> Just an observation ... >>> >>> Jayachandran C. wrote: >>> >>>> Author: jchandra >>>> Date: Wed Aug 4 14:12:09 2010 >>>> New Revision: 210846 >>>> URL: http://svn.freebsd.org/changeset/base/210846 >>>> >>>> Log: >>>> Add 3 level page tables for MIPS in n64. >>>> - 32 bit compilation will still use old 2 level page tables >>>> - re-arrange pmap code so that adding another level is easier >>>> - pmap code for 3 level page tables for n64 >>>> - update TLB handler to traverse 3 levels in n64 >>>> Reviewed by: jmallett >>>> >>> MIPS doesn't really need to use atomic_cmpset_int() in situations like this >>> because the software dirty bit emulation in trap.c acquires the pmap lock. >>> Atomics like this appear to be a carryover from i386 where the >>> hardware-managed TLB might concurrently set the modified bit. >>> >> Then I guess we should be able to use *pte directly, without pbits, >> obits and the retry loop. >> Will try this change... >> > Can you have a look at the attached patch and see if it is okay? This > has the above changes, and I have attempted to fix the other issue you > had reported on wired mapping count too. > > The patch looks good. > There are a few calls for loadandclear() on pte too, with pmap lock > held, can this be avoided too? > > I haven't looked at them, but almost certainly yes. Alan
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