Date: Mon, 15 Dec 2014 22:04:06 -0800 From: Peter Wemm <peter@wemm.org> To: Adrian Chadd <adrian@freebsd.org> Cc: Alfred Perlstein <bright@mu.org>, "freebsd-stable@freebsd.org" <freebsd-stable@freebsd.org>, Ian Lepore <ian@freebsd.org> Subject: Re: i386 PAE kernel works fine on 10-stable Message-ID: <2036758.o6RQzZpOtp@overcee.wemm.org> In-Reply-To: <CAJ-VmokJ=%2BNwAfzoATzaiWD1RsbWeSbb07DLUeYKwCOSCzDuBg@mail.gmail.com> References: <1418579278.2026.9.camel@freebsd.org> <A33FE253-B9EE-46FE-9229-CFBC21A80024@mu.org> <CAJ-VmokJ=%2BNwAfzoATzaiWD1RsbWeSbb07DLUeYKwCOSCzDuBg@mail.gmail.com>
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[-- Attachment #1 --] On Monday, December 15, 2014 05:12:39 PM Adrian Chadd wrote: > On 15 December 2014 at 16:33, Alfred Perlstein <bright@mu.org> wrote: > >> On Dec 15, 2014, at 3:42 PM, Peter Wemm <peter@wemm.org> wrote: > >> > >> It's always been a 1GB/3GB split. It was never a problem until certain > >> scaling defaults were changed to scale solely based on physical ram > >> without > >> regard for kva limits. > > > > Hmm the original patch I gave for that only changed scaling for machines > > with 64 bit pointers. Why was it that the 32 bit stuff was made to > > change? > I recall this - I went digging; commit > > 7beb738c8a72cc197d3e898784afe3fba28f1834 > > removed that particular bit of autotuning based on the size of void *. > > Maybe this stuff is a little busted and we need to add some more > config parameters? > > (Also, there's the vm space shift thing that also needed adjustment > for memory-constrained systems. We've had do it on MIPS and low-memory > (64mb, 128mb) RAM i386 systems.) > > > > -adrian There's more to it than just one commit. There's years of general trends that added scaling by physical ram without regard for kva consumption. The starting point for Alfred's commits a few years ago already didn't work properly on large memory systems. Alfred worked on the scaling for the 64-bit / direct map systems and tried to leave the caps alone for kva-constrained systems. The caps were already too high. Except for i386, kva-limited systems generally are pretty small and are explicitly tuned for "small". The tuning considerations for a 32MB or 64MB mips/arm system is very different than a 16GB i386 PAE system. -- Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com; KI6FJV UTF-8: for when a ' or ... just won\342\200\231t do\342\200\246 [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAABAgAGBQJUj8taAAoJEDXWlwnsgJ4EA/EIAItF3mNK02PQvolcgS4y9fJb kQkNUTKo7gzWTaclcTNQ90OmHmQExs9uOMD/i5EN2thTfil7YmcwlrF+cSrJPb/l 5jEBn4irS/31C59bG4LmwmEuq3QW2kQj9i6l6avZuC3mXcMpRNHYkz/8X2YdXkTn o+DFHQOzB+rGwIjl5aRoO2OZnMjdmxqtSI+OVlU7bOLMEu+TcdbcggsI/kqKHR2X iwFiSokL8Gz8fzBJjrdGCorU71xhhXbaycSK0NmJACiHvXCCXyHx2AglTGuojClg tgDQlG6GOkBK7ymhyCwTtpldWUPUnutD/D01Akjre3DY88YxakkHLQfb6EFOiMU= =iOt5 -----END PGP SIGNATURE-----
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