Date: Mon, 8 Jul 2013 23:30:15 -0700 From: Garrett Cooper <yaneurabeya@gmail.com> To: Attilio Rao <attilio@FreeBSD.org> Cc: alc@FreeBSD.org, swills@FreeBSD.org, jeff@FreeBSD.org, Alfred Perlstein <alfred@freebsd.org>, freebsd-emulation@FreeBSD.org, kib@FreeBSD.org, portmgr@FreeBSD.org, nox@FreeBSD.org, vbox@FreeBSD.org Subject: Re: svn commit: r248084 - in head/sys: amd64/amd64 arm/arm cddl/compat/opensolaris/kern cddl/compat/opensolaris/sys cddl/contrib/opensolaris/uts/common/fs/zfs cddl/contrib/opensolaris/uts/common/fs/zfs... Message-ID: <4952B228-DD42-45FE-9BC7-5D4B43FAF8FF@gmail.com> In-Reply-To: <201303090232.r292WN6W067161@svn.freebsd.org>
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On Mar 8, 2013, at 6:32 PM, Attilio Rao wrote: > Author: attilio > Date: Sat Mar 9 02:32:23 2013 > New Revision: 248084 > URL: http://svnweb.freebsd.org/changeset/base/248084 > > Log: > Switch the vm_object mutex to be a rwlock. This will enable in the > future further optimizations where the vm_object lock will be held > in read mode most of the time the page cache resident pool of pages > are accessed for reading purposes. > > The change is mostly mechanical but few notes are reported: > * The KPI changes as follow: > - VM_OBJECT_LOCK() -> VM_OBJECT_WLOCK() > - VM_OBJECT_TRYLOCK() -> VM_OBJECT_TRYWLOCK() > - VM_OBJECT_UNLOCK() -> VM_OBJECT_WUNLOCK() > - VM_OBJECT_LOCK_ASSERT(MA_OWNED) -> VM_OBJECT_ASSERT_WLOCKED() > (in order to avoid visibility of implementation details) > - The read-mode operations are added: > VM_OBJECT_RLOCK(), VM_OBJECT_TRYRLOCK(), VM_OBJECT_RUNLOCK(), > VM_OBJECT_ASSERT_RLOCKED(), VM_OBJECT_ASSERT_LOCKED() > * The vm/vm_pager.h namespace pollution avoidance (forcing requiring > sys/mutex.h in consumers directly to cater its inlining functions > using VM_OBJECT_LOCK()) imposes that all the vm/vm_pager.h > consumers now must include also sys/rwlock.h. > * zfs requires a quite convoluted fix to include FreeBSD rwlocks into > the compat layer because the name clash between FreeBSD and solaris > versions must be avoided. > At this purpose zfs redefines the vm_object locking functions > directly, isolating the FreeBSD components in specific compat stubs. > > The KPI results heavilly broken by this commit. Thirdy part ports must > be updated accordingly (I can think off-hand of VirtualBox, for example). > > Sponsored by: EMC / Isilon storage division > Reviewed by: jeff > Reviewed by: pjd (ZFS specific review) > Discussed with: alc > Tested by: pho This commit broke emulators/open-vm-tools (which helps with hardware acceleration and other guest OS services on VMware, et al) and it's been broken for ~4 months now. Please ask portmgr@ to do an exp- run before making KPI changes. open-vm-tools, nvidia-driver, qemu*, and virtualbox-ose* are and have been particularly vulnerable to sweeping changes like this in the past (I've had to patch a lot of 3rd party software broken by KPI changes in 10.x, more than in prior releases) and a lot of developers depend on this functionality to be sane in order to develop software on -CURRENT and -STABLE (and it allows us to better test your code). Thanks, -Garretthelp
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