| Message ID | 1346312203-29456-5-git-send-email-levinsasha928@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Aug 30, 2012 at 10:36 AM, Sasha Levin <levinsasha928@gmail.com> wrote: > Build with -flto set, which should enable link-time-optimizations. > > I'm not sure if it provides a significant performance increase, but > it's probably just worth it for catching issues which it may cause. > > Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Ingo, any objections to this? > --- > tools/kvm/Makefile | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/tools/kvm/Makefile b/tools/kvm/Makefile > index 8aa0125..0e2fa66 100644 > --- a/tools/kvm/Makefile > +++ b/tools/kvm/Makefile > @@ -243,7 +243,7 @@ DEFINES += -DKVMTOOLS_VERSION='"$(KVMTOOLS_VERSION)"' > DEFINES += -DBUILD_ARCH='"$(ARCH)"' > > KVM_INCLUDE := include > -CFLAGS += $(CPPFLAGS) $(DEFINES) -I$(KVM_INCLUDE) -I$(ARCH_INCLUDE) -I$(KINCL_PATH)/include -I$(KINCL_PATH)/arch/$(ARCH)/include/ -O2 -fno-strict-aliasing -g > +CFLAGS += $(CPPFLAGS) $(DEFINES) -I$(KVM_INCLUDE) -I$(ARCH_INCLUDE) -I$(KINCL_PATH)/include -I$(KINCL_PATH)/arch/$(ARCH)/include/ -O2 -fno-strict-aliasing -g -flto > > WARNINGS += -Wall > WARNINGS += -Wcast-align > -- > 1.7.12 > > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
* Pekka Enberg <penberg@kernel.org> wrote: > On Thu, Aug 30, 2012 at 10:36 AM, Sasha Levin <levinsasha928@gmail.com> wrote: > > Build with -flto set, which should enable link-time-optimizations. > > > > I'm not sure if it provides a significant performance increase, but > > it's probably just worth it for catching issues which it may cause. > > > > Signed-off-by: Sasha Levin <levinsasha928@gmail.com> > > Ingo, any objections to this? No objections if you can live with a 2x-4x increase in build time - at worst it might cause funnies with the BIOS linker script and such. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Aug 30, 2012 at 10:16:54AM +0200, Ingo Molnar wrote: > > * Pekka Enberg <penberg@kernel.org> wrote: > > > On Thu, Aug 30, 2012 at 10:36 AM, Sasha Levin <levinsasha928@gmail.com> wrote: > > > Build with -flto set, which should enable link-time-optimizations. > > > > > > I'm not sure if it provides a significant performance increase, but > > > it's probably just worth it for catching issues which it may cause. > > > > > > Signed-off-by: Sasha Levin <levinsasha928@gmail.com> > > > > Ingo, any objections to this? > > No objections if you can live with a 2x-4x increase in build > time - at worst it might cause funnies with the BIOS linker > script and such. Maybe we could enable it via some make option? Say make LTO=1 or something? Cyrill -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 08/30/2012 10:22 AM, Cyrill Gorcunov wrote: > On Thu, Aug 30, 2012 at 10:16:54AM +0200, Ingo Molnar wrote: >> >> * Pekka Enberg <penberg@kernel.org> wrote: >> >>> On Thu, Aug 30, 2012 at 10:36 AM, Sasha Levin <levinsasha928@gmail.com> wrote: >>>> Build with -flto set, which should enable link-time-optimizations. >>>> >>>> I'm not sure if it provides a significant performance increase, but >>>> it's probably just worth it for catching issues which it may cause. >>>> >>>> Signed-off-by: Sasha Levin <levinsasha928@gmail.com> >>> >>> Ingo, any objections to this? >> >> No objections if you can live with a 2x-4x increase in build >> time - at worst it might cause funnies with the BIOS linker >> script and such. > > Maybe we could enable it via some make option? > Say make LTO=1 or something? Build time went from 6 sec to 14, I don't think it's that significant... -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Aug 30, 2012 at 10:33:21AM +0200, Sasha Levin wrote: > >>> > >>> Ingo, any objections to this? > >> > >> No objections if you can live with a 2x-4x increase in build > >> time - at worst it might cause funnies with the BIOS linker > >> script and such. > > > > Maybe we could enable it via some make option? > > Say make LTO=1 or something? > > Build time went from 6 sec to 14, I don't think it's that significant... At moment. But I bet lkvm will grow with time and build time increase as well. Still if you think we better stick with LTO, no problem, lets do it then ;) Cyrill -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Aug 30, 2012 at 11:22 AM, Cyrill Gorcunov <gorcunov@openvz.org> wrote: > Maybe we could enable it via some make option? > Say make LTO=1 or something? That is not going to help much in catching LTO issues early. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/tools/kvm/Makefile b/tools/kvm/Makefile index 8aa0125..0e2fa66 100644 --- a/tools/kvm/Makefile +++ b/tools/kvm/Makefile @@ -243,7 +243,7 @@ DEFINES += -DKVMTOOLS_VERSION='"$(KVMTOOLS_VERSION)"' DEFINES += -DBUILD_ARCH='"$(ARCH)"' KVM_INCLUDE := include -CFLAGS += $(CPPFLAGS) $(DEFINES) -I$(KVM_INCLUDE) -I$(ARCH_INCLUDE) -I$(KINCL_PATH)/include -I$(KINCL_PATH)/arch/$(ARCH)/include/ -O2 -fno-strict-aliasing -g +CFLAGS += $(CPPFLAGS) $(DEFINES) -I$(KVM_INCLUDE) -I$(ARCH_INCLUDE) -I$(KINCL_PATH)/include -I$(KINCL_PATH)/arch/$(ARCH)/include/ -O2 -fno-strict-aliasing -g -flto WARNINGS += -Wall WARNINGS += -Wcast-align
Build with -flto set, which should enable link-time-optimizations. I'm not sure if it provides a significant performance increase, but it's probably just worth it for catching issues which it may cause. Signed-off-by: Sasha Levin <levinsasha928@gmail.com> --- tools/kvm/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)