| Message ID | 20240323080541.10047-2-pmenzel@molgen.mpg.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: VMX: make vmx_init a late init call to get to init process faster | expand |
[CC: Update Colin’s address.] Am 23.03.24 um 09:05 schrieb Paul Menzel: > From: Colin Ian King <colin.i.king@intel.com> > > Making vmx_init a late initcall improves QEMU kernel boot times to > get to the init process. Average of 100 boots, QEMU boot average > reduced from 0.776 seconds to 0.622 seconds (~19.8% faster) on > Alder Lake i9-12900 and ~0.5% faster for non-QEMU UEFI boots. > > Signed-off-by: Colin Ian King <colin.i.king@intel.com> > [Take patch > https://github.com/clearlinux-pkgs/linux/commit/797db35496031b19ba37b1639ac5fa5db9159a06 > and fix spelling of Alder Lake.] > Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de> > --- > arch/x86/kvm/vmx/vmx.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index c37a89eda90f..0a9f4b20fbda 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -8783,4 +8783,4 @@ static int __init vmx_init(void) > kvm_x86_vendor_exit(); > return r; > } > -module_init(vmx_init); > +late_initcall(vmx_init)
On Sat, Mar 23, 2024, Paul Menzel wrote: > From: Colin Ian King <colin.i.king@intel.com> > > Making vmx_init a late initcall improves QEMU kernel boot times to > get to the init process. Average of 100 boots, QEMU boot average > reduced from 0.776 seconds to 0.622 seconds (~19.8% faster) on > Alder Lake i9-12900 and ~0.5% faster for non-QEMU UEFI boots. The changelog needs to better explain what "QEMU kernel boot times" means. I assume the test is a QEMU VM running a kernel KVM_INTEL built-in? This should also call out that late_initcall is #defined to module_init() when KVM is built as a module. > Signed-off-by: Colin Ian King <colin.i.king@intel.com> > [Take patch > https://github.com/clearlinux-pkgs/linux/commit/797db35496031b19ba37b1639ac5fa5db9159a06 > and fix spelling of Alder Lake.] > Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de> > --- > arch/x86/kvm/vmx/vmx.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index c37a89eda90f..0a9f4b20fbda 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -8783,4 +8783,4 @@ static int __init vmx_init(void) > kvm_x86_vendor_exit(); > return r; > } > -module_init(vmx_init); > +late_initcall(vmx_init); _If_ we do this, then we should also give svm_init() and kvm_x86_init() the same treatment. I see no reason for vmx_init() to be special. I'm not opposed to this, but I also have zero idea if this could have a negative impact userspace. E.g. what happens if some setup's init process expects /dev/kvm to exist? Will this break that?
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index c37a89eda90f..0a9f4b20fbda 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -8783,4 +8783,4 @@ static int __init vmx_init(void) kvm_x86_vendor_exit(); return r; } -module_init(vmx_init); +late_initcall(vmx_init);