Date: Thu, 30 Mar 2000 08:51:34 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Peter Wemm <peter@netplex.com.au> Cc: "Daniel O'Connor" <doconnor@gsoft.com.au>, cvs-all@FreeBSD.ORG, cvs-committers@FreeBSD.ORG Subject: Re: cvs commit: src/sys/alpha/include vmparam.h src/sys/conf opt Message-ID: <200003301651.IAA73393@apollo.backplane.com> References: <20000330104700.44DEE1CD7@overcee.netplex.com.au>
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:
:Matthew Dillon wrote:
:> :
:> :"Daniel O'Connor" wrote:
:> :>
:> :> On 30-Mar-00 Peter Wemm wrote:
:> :> > that comment is bogus.. The only practical limit is how much physica
: l
:> :> > ram you want to lock up as this stuff isn't paged out or swap backed.
:> :>
:> :> Is it [easily] possible to make its pageable?
:> :
:> :I don't know. Probably, if one wanted to cut/paste code from the likes
:> :of the swap-backed code in the vn device.
:>
:> I couldn't find the beginning of this thread, but if you are talking
:> about making the PV entries pageable, it isn't possible.
:
:No, the shared memory segments themselves, not the PV entries. Presently
:the pages are wired directly into the processes that attach to them and
:they are not pageable. (which is a distinct advantage over using mmap for
:temporary storage if you don't want pagedaemon messing with it - even for
:MAP_ANON)
:
:Cheers,
:-Peter
I'm still confused. SysV shared memory segments are swap-backed.
Even if they weren't, the useage pattern may be random enough that it
won't save on the PV entries or page table pages.
-Matt
Matthew Dillon
<dillon@backplane.com>
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