"David" == David McDaniel <(damcdani)" <[EMAIL PROTECTED]>> writes:
David> Thanks for the clarification. Pending the successful outcome of the David> project you mention, your use of the phrase "private anonymous memory" David> intrigues me and thus I'll ask about an idea I had to finess this issue. Hmm, I'm not sure what the right term is. I'm referring to memory created with mmap() with the (MAP_ANON|MAP_PRIVATE) flags. David> Lets say I have a process whose sole task is to export a memory David> region. It would set the heap page size to 4m, allocate a suitably sized David> and aligned block of autonymous memory, possibly by mapping /dev/zero or David> whatever. Then it could read the contents of these files that our David> process mmap today. Then,it could change the permissions and attributes David> of the region to shared and then publish this address by some means. If David> I understand things, some other process could open /proc/<pid>/as and David> mmap that offset, yielding shared large pages. If you create a heap large enough (typically 6MB on a SPARC-based system), LPOOB will set the heap page size to 4MB, but if you wanted to make sure, you could use memcntl(). If you map /dev/zero, that's going to a separate segment, not the heap. I'm not what happens if you try to mmap() /dev/zero into the heap, but I suspect it fails. What you're doing sounds like (intimate) shared memory to me. You somehow have to read the data into that memory. David> Any obvious hole in that thinking? Well, proc(4) says you can do stuff like that, so I guess it would work. >> -----Original Message----- >> From: Dave Marquardt [mailto:[EMAIL PROTECTED] >> Sent: Wednesday, October 05, 2005 8:25 AM >> To: David McDaniel (damcdani) >> Cc: perf-discuss@opensolaris.org >> Subject: Re: [perf-discuss] General question re large pages OOB >> >> "David" == David McDaniel <[EMAIL PROTECTED]> writes: >> David> Hi all. I've heard of the effort to broaden the use of large David> pages to cover things besides anonymous memory. The >> application I David> workon has the properties of (1) "sharing" gigabytes of memory David> between process by way of memory mapped files and alas David> (2) being dragged down by dtlb and dtsb miss rates. So >> I wanted David> to know if this effort would enable us to map these files into David> large pages to improve the situation. Thanks -d >> >> Sorry, no, LPOOB covers heap, stack and private anonymous memory. >> However, memcntl()'s MC_HAT_ADVISE interface has been >> extended (by another large page project, MPSS for Vnodes) to >> work with regular files. >> -- >> Dave Marquardt >> Sun Microsystems, Inc. >> Austin, TX >> +1 512 401-1077 >> -- Dave Marquardt Sun Microsystems, Inc. Austin, TX +1 512 401-1077 _______________________________________________ perf-discuss mailing list perf-discuss@opensolaris.org
