| Message ID | 1368738782-18649-3-git-send-email-xiaoguangrong@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, May 17, 2013 at 05:12:57AM +0800, Xiao Guangrong wrote: > Move deletion shadow page from the hash list from kvm_mmu_commit_zap_page to > kvm_mmu_prepare_zap_page so that we can call kvm_mmu_commit_zap_page > once for multiple kvm_mmu_prepare_zap_page that can help us to avoid > unnecessary TLB flush > Don't we call kvm_mmu_commit_zap_page() once for multiple kvm_mmu_prepare_zap_page() now when possible? kvm_mmu_commit_zap_page() gets a list as a parameter. I am not against the change, but wish to understand it better. > Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> > --- > arch/x86/kvm/mmu.c | 8 ++++++-- > 1 files changed, 6 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > index 40d7b2d..682ecb4 100644 > --- a/arch/x86/kvm/mmu.c > +++ b/arch/x86/kvm/mmu.c > @@ -1466,7 +1466,7 @@ static inline void kvm_mod_used_mmu_pages(struct kvm *kvm, int nr) > static void kvm_mmu_free_page(struct kvm_mmu_page *sp) > { > ASSERT(is_empty_shadow_page(sp->spt)); > - hlist_del(&sp->hash_link); > + > list_del(&sp->link); > free_page((unsigned long)sp->spt); > if (!sp->role.direct) > @@ -1655,7 +1655,8 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm, > > #define for_each_gfn_indirect_valid_sp(_kvm, _sp, _gfn) \ > for_each_gfn_sp(_kvm, _sp, _gfn) \ > - if ((_sp)->role.direct || (_sp)->role.invalid) {} else > + if ((_sp)->role.direct || \ > + ((_sp)->role.invalid && WARN_ON(1))) {} else > > /* @sp->gfn should be write-protected at the call site */ > static int __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, > @@ -2074,6 +2075,9 @@ static int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, > unaccount_shadowed(kvm, sp->gfn); > if (sp->unsync) > kvm_unlink_unsync_page(kvm, sp); > + > + hlist_del_init(&sp->hash_link); > + What about moving this inside if() bellow and making it hlist_del()? Leave the page on the hash if root_count is non zero. > if (!sp->root_count) { > /* Count self */ > ret++; > -- > 1.7.7.6 -- Gleb. -- 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 05/19/2013 06:47 PM, Gleb Natapov wrote: > On Fri, May 17, 2013 at 05:12:57AM +0800, Xiao Guangrong wrote: >> Move deletion shadow page from the hash list from kvm_mmu_commit_zap_page to >> kvm_mmu_prepare_zap_page so that we can call kvm_mmu_commit_zap_page >> once for multiple kvm_mmu_prepare_zap_page that can help us to avoid >> unnecessary TLB flush >> > Don't we call kvm_mmu_commit_zap_page() once for multiple > kvm_mmu_prepare_zap_page() now when possible? kvm_mmu_commit_zap_page() > gets a list as a parameter. I am not against the change, but wish to > understand it better. The changelong is not clear enough, i mean we can "call kvm_mmu_commit_zap_page once for multiple kvm_mmu_prepare_zap_page" when we use lock-break technique. If we do not do this, the page can be found in hashtable but they are linked on the invalid_list on other thread. > >> Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> >> --- >> arch/x86/kvm/mmu.c | 8 ++++++-- >> 1 files changed, 6 insertions(+), 2 deletions(-) >> >> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c >> index 40d7b2d..682ecb4 100644 >> --- a/arch/x86/kvm/mmu.c >> +++ b/arch/x86/kvm/mmu.c >> @@ -1466,7 +1466,7 @@ static inline void kvm_mod_used_mmu_pages(struct kvm *kvm, int nr) >> static void kvm_mmu_free_page(struct kvm_mmu_page *sp) >> { >> ASSERT(is_empty_shadow_page(sp->spt)); >> - hlist_del(&sp->hash_link); >> + >> list_del(&sp->link); >> free_page((unsigned long)sp->spt); >> if (!sp->role.direct) >> @@ -1655,7 +1655,8 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm, >> >> #define for_each_gfn_indirect_valid_sp(_kvm, _sp, _gfn) \ >> for_each_gfn_sp(_kvm, _sp, _gfn) \ >> - if ((_sp)->role.direct || (_sp)->role.invalid) {} else >> + if ((_sp)->role.direct || \ >> + ((_sp)->role.invalid && WARN_ON(1))) {} else >> >> /* @sp->gfn should be write-protected at the call site */ >> static int __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, >> @@ -2074,6 +2075,9 @@ static int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, >> unaccount_shadowed(kvm, sp->gfn); >> if (sp->unsync) >> kvm_unlink_unsync_page(kvm, sp); >> + >> + hlist_del_init(&sp->hash_link); >> + > What about moving this inside if() bellow and making it hlist_del()? > Leave the page on the hash if root_count is non zero. > It's a good idea. will update. -- 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 Mon, May 20, 2013 at 05:19:26PM +0800, Xiao Guangrong wrote: > On 05/19/2013 06:47 PM, Gleb Natapov wrote: > > On Fri, May 17, 2013 at 05:12:57AM +0800, Xiao Guangrong wrote: > >> Move deletion shadow page from the hash list from kvm_mmu_commit_zap_page to > >> kvm_mmu_prepare_zap_page so that we can call kvm_mmu_commit_zap_page > >> once for multiple kvm_mmu_prepare_zap_page that can help us to avoid > >> unnecessary TLB flush > >> > > Don't we call kvm_mmu_commit_zap_page() once for multiple > > kvm_mmu_prepare_zap_page() now when possible? kvm_mmu_commit_zap_page() > > gets a list as a parameter. I am not against the change, but wish to > > understand it better. > > The changelong is not clear enough, i mean we can "call > kvm_mmu_commit_zap_page once for multiple kvm_mmu_prepare_zap_page" when > we use lock-break technique. If we do not do this, the page can be found > in hashtable but they are linked on the invalid_list on other thread. > Got it. Make sense. > > > >> Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> > >> --- > >> arch/x86/kvm/mmu.c | 8 ++++++-- > >> 1 files changed, 6 insertions(+), 2 deletions(-) > >> > >> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > >> index 40d7b2d..682ecb4 100644 > >> --- a/arch/x86/kvm/mmu.c > >> +++ b/arch/x86/kvm/mmu.c > >> @@ -1466,7 +1466,7 @@ static inline void kvm_mod_used_mmu_pages(struct kvm *kvm, int nr) > >> static void kvm_mmu_free_page(struct kvm_mmu_page *sp) > >> { > >> ASSERT(is_empty_shadow_page(sp->spt)); > >> - hlist_del(&sp->hash_link); > >> + > >> list_del(&sp->link); > >> free_page((unsigned long)sp->spt); > >> if (!sp->role.direct) > >> @@ -1655,7 +1655,8 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm, > >> > >> #define for_each_gfn_indirect_valid_sp(_kvm, _sp, _gfn) \ > >> for_each_gfn_sp(_kvm, _sp, _gfn) \ > >> - if ((_sp)->role.direct || (_sp)->role.invalid) {} else > >> + if ((_sp)->role.direct || \ > >> + ((_sp)->role.invalid && WARN_ON(1))) {} else > >> > >> /* @sp->gfn should be write-protected at the call site */ > >> static int __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, > >> @@ -2074,6 +2075,9 @@ static int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, > >> unaccount_shadowed(kvm, sp->gfn); > >> if (sp->unsync) > >> kvm_unlink_unsync_page(kvm, sp); > >> + > >> + hlist_del_init(&sp->hash_link); > >> + > > What about moving this inside if() bellow and making it hlist_del()? > > Leave the page on the hash if root_count is non zero. > > > > It's a good idea. will update. > -- Gleb. -- 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/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 40d7b2d..682ecb4 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -1466,7 +1466,7 @@ static inline void kvm_mod_used_mmu_pages(struct kvm *kvm, int nr) static void kvm_mmu_free_page(struct kvm_mmu_page *sp) { ASSERT(is_empty_shadow_page(sp->spt)); - hlist_del(&sp->hash_link); + list_del(&sp->link); free_page((unsigned long)sp->spt); if (!sp->role.direct) @@ -1655,7 +1655,8 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm, #define for_each_gfn_indirect_valid_sp(_kvm, _sp, _gfn) \ for_each_gfn_sp(_kvm, _sp, _gfn) \ - if ((_sp)->role.direct || (_sp)->role.invalid) {} else + if ((_sp)->role.direct || \ + ((_sp)->role.invalid && WARN_ON(1))) {} else /* @sp->gfn should be write-protected at the call site */ static int __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, @@ -2074,6 +2075,9 @@ static int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, unaccount_shadowed(kvm, sp->gfn); if (sp->unsync) kvm_unlink_unsync_page(kvm, sp); + + hlist_del_init(&sp->hash_link); + if (!sp->root_count) { /* Count self */ ret++;
Move deletion shadow page from the hash list from kvm_mmu_commit_zap_page to kvm_mmu_prepare_zap_page so that we can call kvm_mmu_commit_zap_page once for multiple kvm_mmu_prepare_zap_page that can help us to avoid unnecessary TLB flush Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> --- arch/x86/kvm/mmu.c | 8 ++++++-- 1 files changed, 6 insertions(+), 2 deletions(-)