Date: Sat, 31 Dec 2011 13:24:53 +0000 (UTC) From: Gavin Atkinson <gavin@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r229085 - in head/sys: amd64/amd64 i386/i386 Message-ID: <201112311324.pBVDOriM065030@svn.freebsd.org>
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Author: gavin Date: Sat Dec 31 13:24:53 2011 New Revision: 229085 URL: http://svn.freebsd.org/changeset/base/229085 Log: Default to not performing the early-boot memory tests when we detect we are booting inside a VM. There are three reasons to disable this: o It causes the VM host to believe that all the tested pages or RAM are in use. This in turn may force the host to page out pages of RAM belonging to other VMs, or otherwise cause problems with fair resource sharing on the VM cluster. o It adds significant time to the boot process (around 1 second/Gig in testing) o It is unnecessary - the host should have already verified that the memory is functional etc. Note that this simply changes the default when in a VM - it can still be overridden using the hw.memtest.tests tunable. MFC after: 4 weeks Modified: head/sys/amd64/amd64/machdep.c head/sys/i386/i386/machdep.c Modified: head/sys/amd64/amd64/machdep.c ============================================================================== --- head/sys/amd64/amd64/machdep.c Sat Dec 31 13:23:04 2011 (r229084) +++ head/sys/amd64/amd64/machdep.c Sat Dec 31 13:24:53 2011 (r229085) @@ -1401,10 +1401,13 @@ getmemsize(caddr_t kmdp, u_int64_t first Maxmem = atop(physmem_tunable); /* - * By default keep the memtest enabled. Use a general name so that + * By default enable the memory test on real hardware, and disable + * it if we appear to be running in a VM. This avoids touching all + * pages unnecessarily, which doesn't matter on real hardware but is + * bad for shared VM hosts. Use a general name so that * one could eventually do more with the code than just disable it. */ - memtest = 1; + memtest = (vm_guest > VM_GUEST_NO) ? 0 : 1; TUNABLE_ULONG_FETCH("hw.memtest.tests", &memtest); /* Modified: head/sys/i386/i386/machdep.c ============================================================================== --- head/sys/i386/i386/machdep.c Sat Dec 31 13:23:04 2011 (r229084) +++ head/sys/i386/i386/machdep.c Sat Dec 31 13:24:53 2011 (r229085) @@ -2369,10 +2369,13 @@ physmap_done: Maxmem = atop(physmap[physmap_idx + 1]); /* - * By default keep the memtest enabled. Use a general name so that + * By default enable the memory test on real hardware, and disable + * it if we appear to be running in a VM. This avoids touching all + * pages unnecessarily, which doesn't matter on real hardware but is + * bad for shared VM hosts. Use a general name so that * one could eventually do more with the code than just disable it. */ - memtest = 1; + memtest = (vm_guest > VM_GUEST_NO) ? 0 : 1; TUNABLE_ULONG_FETCH("hw.memtest.tests", &memtest); if (atop(physmap[physmap_idx + 1]) != Maxmem &&
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