From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757920Ab3JQQBO (ORCPT ); Thu, 17 Oct 2013 12:01:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:4156 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756377Ab3JQQBL (ORCPT ); Thu, 17 Oct 2013 12:01:11 -0400 Date: Thu, 17 Oct 2013 12:00:34 -0400 From: Don Zickus To: Peter Zijlstra Cc: Andi Kleen , dave.hansen@linux.intel.com, eranian@google.com, jmario@redhat.com, linux-kernel@vger.kernel.org, acme@infradead.org, mingo@kernel.org Subject: Re: [PATCH] perf, x86: Optimize intel_pmu_pebs_fixup_ip() Message-ID: <20131017160034.GO227855@redhat.com> References: <20131015101404.GD10651@twins.programming.kicks-ass.net> <20131015130226.GX26785@twins.programming.kicks-ass.net> <20131015143227.GY26785@twins.programming.kicks-ass.net> <20131015150736.GZ26785@twins.programming.kicks-ass.net> <20131015154104.GA227855@redhat.com> <20131016105755.GX10651@twins.programming.kicks-ass.net> <20131016205227.GJ7456@tassilo.jf.intel.com> <20131016210319.GI10651@twins.programming.kicks-ass.net> <20131016230712.GC26785@twins.programming.kicks-ass.net> <20131017094145.GE3364@laptop.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131017094145.GE3364@laptop.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 17, 2013 at 11:41:45AM +0200, Peter Zijlstra wrote: > On Thu, Oct 17, 2013 at 01:07:12AM +0200, Peter Zijlstra wrote: > > On Wed, Oct 16, 2013 at 11:03:19PM +0200, Peter Zijlstra wrote: > > > Anyway; if you want to have a go at this, feel free. > > > > OK, couldn't help myself; completely untested patch below. > > > > I think the full once copy it best for the decode as even with the below > > interface you'd end up doing a lot of duplicate copying due to the > > variable size insn mess. > > Duh, a very small tweak would make it work for that and avoid most of > the memcpy()s. Hmm, for some reason, even though copy_from_user_nmi_iter is super fast now, the while(to < ip) count increased dramatically and so did my latency. :-( Not sure what happened between your pretty patch yesterday and this direction. Cheers, Don > > --- > arch/x86/include/asm/uaccess.h | 13 +++++ > arch/x86/kernel/cpu/perf_event.c | 32 +++++------ > arch/x86/kernel/cpu/perf_event_intel_ds.c | 21 ++++--- > arch/x86/lib/usercopy.c | 91 ++++++++++++++++++++++++++++++- > arch/x86/mm/gup.c | 63 +++++++++++++-------- > 5 files changed, 165 insertions(+), 55 deletions(-) > > diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h > index 5838fa911aa0..a341de0eadd1 100644 > --- a/arch/x86/include/asm/uaccess.h > +++ b/arch/x86/include/asm/uaccess.h > @@ -516,6 +516,19 @@ struct __large_struct { unsigned long buf[100]; }; > > extern unsigned long > copy_from_user_nmi(void *to, const void __user *from, unsigned long n); > + > +struct copy_from_user_nmi_state { > + void *map; > + unsigned long address; > + unsigned long flags; > +}; > + > +extern void * > +copy_from_user_nmi_iter(void *to, const void __user *from, > + unsigned long n, struct copy_from_user_nmi_state *state); > +extern void > +copy_from_user_nmi_end(struct copy_from_user_nmi_state *state); > + > extern __must_check long > strncpy_from_user(char *dst, const char __user *src, long count); > > diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c > index 19c9d86d2f04..c917fe470861 100644 > --- a/arch/x86/kernel/cpu/perf_event.c > +++ b/arch/x86/kernel/cpu/perf_event.c > @@ -1979,8 +1979,9 @@ static inline int > perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry *entry) > { > /* 32-bit process in 64-bit kernel. */ > + struct copy_from_user_nmi_state state = { NULL }; > unsigned long ss_base, cs_base; > - struct stack_frame_ia32 frame; > + struct stack_frame_ia32 frame, *f; > const void __user *fp; > > if (!test_thread_flag(TIF_IA32)) > @@ -1991,20 +1992,17 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry *entry) > > fp = compat_ptr(ss_base + regs->bp); > while (entry->nr < PERF_MAX_STACK_DEPTH) { > - unsigned long bytes; > - frame.next_frame = 0; > - frame.return_address = 0; > - > - bytes = copy_from_user_nmi(&frame, fp, sizeof(frame)); > - if (bytes != sizeof(frame)) > + f = copy_from_user_nmi_iter(&frame, fp, sizeof(frame), &state); > + if (!f) > break; > > if (!valid_user_frame(fp, sizeof(frame))) > break; > > - perf_callchain_store(entry, cs_base + frame.return_address); > - fp = compat_ptr(ss_base + frame.next_frame); > + perf_callchain_store(entry, cs_base + f->return_address); > + fp = compat_ptr(ss_base + f->next_frame); > } > + copy_from_user_nmi_end(&state); > return 1; > } > #else > @@ -2018,7 +2016,8 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry *entry) > void > perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs) > { > - struct stack_frame frame; > + struct copy_from_user_nmi_state state = { NULL }; > + struct stack_frame frame, *f; > const void __user *fp; > > if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { > @@ -2043,20 +2042,17 @@ perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs) > return; > > while (entry->nr < PERF_MAX_STACK_DEPTH) { > - unsigned long bytes; > - frame.next_frame = NULL; > - frame.return_address = 0; > - > - bytes = copy_from_user_nmi(&frame, fp, sizeof(frame)); > - if (bytes != sizeof(frame)) > + f = copy_from_user_nmi_iter(&frame, fp, sizeof(frame), &state); > + if (!f) > break; > > if (!valid_user_frame(fp, sizeof(frame))) > break; > > - perf_callchain_store(entry, frame.return_address); > - fp = frame.next_frame; > + perf_callchain_store(entry, f->return_address); > + fp = f->next_frame; > } > + copy_from_user_nmi_end(&state); > } > > /* > diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c > index 32e9ed81cd00..5bd3f2091da9 100644 > --- a/arch/x86/kernel/cpu/perf_event_intel_ds.c > +++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c > @@ -725,10 +725,14 @@ void intel_pmu_pebs_disable_all(void) > static int intel_pmu_pebs_fixup_ip(struct pt_regs *regs) > { > struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events); > + struct copy_from_user_nmi_state state = { NULL }; > unsigned long from = cpuc->lbr_entries[0].from; > unsigned long old_to, to = cpuc->lbr_entries[0].to; > unsigned long ip = regs->ip; > + u8 buf[MAX_INSN_SIZE]; > + struct insn insn; > int is_64bit = 0; > + void *kaddr; > > /* > * We don't need to fixup if the PEBS assist is fault like > @@ -764,19 +768,12 @@ static int intel_pmu_pebs_fixup_ip(struct pt_regs *regs) > } > > do { > - struct insn insn; > - u8 buf[MAX_INSN_SIZE]; > - void *kaddr; > - > old_to = to; > if (!kernel_ip(ip)) { > - int bytes, size = MAX_INSN_SIZE; > - > - bytes = copy_from_user_nmi(buf, (void __user *)to, size); > - if (bytes != size) > - return 0; > - > - kaddr = buf; > + kaddr = copy_from_user_nmi_iter(buf, (void __user *)to, > + MAX_INSN_SIZE, &state); > + if (!kaddr) > + break; > } else > kaddr = (void *)to; > > @@ -788,6 +785,8 @@ static int intel_pmu_pebs_fixup_ip(struct pt_regs *regs) > to += insn.length; > } while (to < ip); > > + copy_from_user_nmi_end(&state); > + > if (to == ip) { > set_linear_ip(regs, old_to); > return 1; > diff --git a/arch/x86/lib/usercopy.c b/arch/x86/lib/usercopy.c > index 4f74d94c8d97..da6c36a8b842 100644 > --- a/arch/x86/lib/usercopy.c > +++ b/arch/x86/lib/usercopy.c > @@ -10,6 +10,8 @@ > #include > #include > > +extern int ___get_user_pages_fast(unsigned long start, int nr_pages, int flags, > + struct page **pages); > /* > * best effort, GUP based copy_from_user() that is NMI-safe > */ > @@ -18,6 +20,7 @@ copy_from_user_nmi(void *to, const void __user *from, unsigned long n) > { > unsigned long offset, addr = (unsigned long)from; > unsigned long size, len = 0; > + unsigned long flags; > struct page *page; > void *map; > int ret; > @@ -26,9 +29,12 @@ copy_from_user_nmi(void *to, const void __user *from, unsigned long n) > return len; > > do { > - ret = __get_user_pages_fast(addr, 1, 0, &page); > - if (!ret) > + local_irq_save(flags); > + ret = ___get_user_pages_fast(addr, 1, 0, &page); > + if (!ret) { > + local_irq_restore(flags); > break; > + } > > offset = addr & (PAGE_SIZE - 1); > size = min(PAGE_SIZE - offset, n - len); > @@ -36,7 +42,7 @@ copy_from_user_nmi(void *to, const void __user *from, unsigned long n) > map = kmap_atomic(page); > memcpy(to, map+offset, size); > kunmap_atomic(map); > - put_page(page); > + local_irq_restore(flags); > > len += size; > to += size; > @@ -47,3 +53,82 @@ copy_from_user_nmi(void *to, const void __user *from, unsigned long n) > return len; > } > EXPORT_SYMBOL_GPL(copy_from_user_nmi); > + > +void *copy_from_user_nmi_iter(void *to, const void __user *from, > + unsigned long n, struct copy_from_user_nmi_state *state) > +{ > + unsigned long offset, addr = (unsigned long)from; > + unsigned long size, len = 0; > + unsigned long flags; > + struct page *page; > + void *map, *_to = to; > + int ret; > + > + if (__range_not_ok(from, n, TASK_SIZE)) > + return NULL; > + > + if (state->map) { > + if ((state->address >> PAGE_SHIFT) == > + (addr >> PAGE_SHIFT)) { > + flags = state->flags; > + map = state->map; > + goto got_page; > + } > + kunmap_atomic(state->map); > + local_irq_restore(state->flags); > + } > + > + for (;;) { > + local_irq_save(flags); > + ret = ___get_user_pages_fast(addr, 1, 0, &page); > + if (!ret) { > + local_irq_restore(flags); > + state->map = NULL; > + return NULL; > + } > + > + map = kmap_atomic(page); > + > +got_page: > + offset = addr & (PAGE_SIZE - 1); > + size = min(PAGE_SIZE - offset, n - len); > + > + /* > + * If the entire desired range falls within the one page > + * avoid the copy and return a pointer into the kmap. > + */ > + if (size == n) { > + _to = map + offset; > + break; > + } > + > + memcpy(to, map+offset, size); > + len += size; > + > + if (len == n) > + break; > + > + to += size; > + addr += size; > + > + kunmap_atomic(map); > + local_irq_restore(flags); > + } > + > + state->address = addr; > + state->flags = flags; > + state->map = map; > + > + return _to; > +} > +EXPORT_SYMBOL_GPL(copy_from_user_nmi_iter); > + > +void copy_from_user_nmi_end(struct copy_from_user_nmi_state *state) > +{ > + if (state->map) { > + kunmap_atomic(state->map); > + local_irq_restore(state->flags); > + state->map = NULL; > + } > +} > +EXPORT_SYMBOL_GPL(copy_from_user_nmi_end); > diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c > index dd74e46828c0..e383caf323e4 100644 > --- a/arch/x86/mm/gup.c > +++ b/arch/x86/mm/gup.c > @@ -63,19 +63,22 @@ static inline pte_t gup_get_pte(pte_t *ptep) > #endif > } > > +#define GUPF_GET 0x01 > +#define GUPF_WRITE 0x02 > + > /* > * The performance critical leaf functions are made noinline otherwise gcc > * inlines everything into a single function which results in too much > * register pressure. > */ > static noinline int gup_pte_range(pmd_t pmd, unsigned long addr, > - unsigned long end, int write, struct page **pages, int *nr) > + unsigned long end, int flags, struct page **pages, int *nr) > { > unsigned long mask; > pte_t *ptep; > > mask = _PAGE_PRESENT|_PAGE_USER; > - if (write) > + if (flags & GUPF_WRITE) > mask |= _PAGE_RW; > > ptep = pte_offset_map(&pmd, addr); > @@ -89,7 +92,8 @@ static noinline int gup_pte_range(pmd_t pmd, unsigned long addr, > } > VM_BUG_ON(!pfn_valid(pte_pfn(pte))); > page = pte_page(pte); > - get_page(page); > + if (flags & GUPF_GET) > + get_page(page); > SetPageReferenced(page); > pages[*nr] = page; > (*nr)++; > @@ -109,7 +113,7 @@ static inline void get_head_page_multiple(struct page *page, int nr) > } > > static noinline int gup_huge_pmd(pmd_t pmd, unsigned long addr, > - unsigned long end, int write, struct page **pages, int *nr) > + unsigned long end, int flags, struct page **pages, int *nr) > { > unsigned long mask; > pte_t pte = *(pte_t *)&pmd; > @@ -117,7 +121,7 @@ static noinline int gup_huge_pmd(pmd_t pmd, unsigned long addr, > int refs; > > mask = _PAGE_PRESENT|_PAGE_USER; > - if (write) > + if (flags & GUPF_WRITE) > mask |= _PAGE_RW; > if ((pte_flags(pte) & mask) != mask) > return 0; > @@ -131,19 +135,20 @@ static noinline int gup_huge_pmd(pmd_t pmd, unsigned long addr, > do { > VM_BUG_ON(compound_head(page) != head); > pages[*nr] = page; > - if (PageTail(page)) > + if ((flags & GUPF_GET) && PageTail(page)) > get_huge_page_tail(page); > (*nr)++; > page++; > refs++; > } while (addr += PAGE_SIZE, addr != end); > - get_head_page_multiple(head, refs); > + if (flags & GUPF_GET) > + get_head_page_multiple(head, refs); > > return 1; > } > > static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end, > - int write, struct page **pages, int *nr) > + int flags, struct page **pages, int *nr) > { > unsigned long next; > pmd_t *pmdp; > @@ -167,10 +172,10 @@ static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end, > if (pmd_none(pmd) || pmd_trans_splitting(pmd)) > return 0; > if (unlikely(pmd_large(pmd))) { > - if (!gup_huge_pmd(pmd, addr, next, write, pages, nr)) > + if (!gup_huge_pmd(pmd, addr, next, flags, pages, nr)) > return 0; > } else { > - if (!gup_pte_range(pmd, addr, next, write, pages, nr)) > + if (!gup_pte_range(pmd, addr, next, flags, pages, nr)) > return 0; > } > } while (pmdp++, addr = next, addr != end); > @@ -179,7 +184,7 @@ static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end, > } > > static noinline int gup_huge_pud(pud_t pud, unsigned long addr, > - unsigned long end, int write, struct page **pages, int *nr) > + unsigned long end, int flags, struct page **pages, int *nr) > { > unsigned long mask; > pte_t pte = *(pte_t *)&pud; > @@ -187,7 +192,7 @@ static noinline int gup_huge_pud(pud_t pud, unsigned long addr, > int refs; > > mask = _PAGE_PRESENT|_PAGE_USER; > - if (write) > + if (flags & GUPF_WRITE) > mask |= _PAGE_RW; > if ((pte_flags(pte) & mask) != mask) > return 0; > @@ -201,19 +206,20 @@ static noinline int gup_huge_pud(pud_t pud, unsigned long addr, > do { > VM_BUG_ON(compound_head(page) != head); > pages[*nr] = page; > - if (PageTail(page)) > + if ((flags & GUPF_GET) && PageTail(page)) > get_huge_page_tail(page); > (*nr)++; > page++; > refs++; > } while (addr += PAGE_SIZE, addr != end); > - get_head_page_multiple(head, refs); > + if (flags & GUPF_GET) > + get_head_page_multiple(head, refs); > > return 1; > } > > static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end, > - int write, struct page **pages, int *nr) > + int flags, struct page **pages, int *nr) > { > unsigned long next; > pud_t *pudp; > @@ -226,10 +232,10 @@ static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end, > if (pud_none(pud)) > return 0; > if (unlikely(pud_large(pud))) { > - if (!gup_huge_pud(pud, addr, next, write, pages, nr)) > + if (!gup_huge_pud(pud, addr, next, flags, pages, nr)) > return 0; > } else { > - if (!gup_pmd_range(pud, addr, next, write, pages, nr)) > + if (!gup_pmd_range(pud, addr, next, flags, pages, nr)) > return 0; > } > } while (pudp++, addr = next, addr != end); > @@ -241,13 +247,12 @@ static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end, > * Like get_user_pages_fast() except its IRQ-safe in that it won't fall > * back to the regular GUP. > */ > -int __get_user_pages_fast(unsigned long start, int nr_pages, int write, > +int ___get_user_pages_fast(unsigned long start, int nr_pages, int flags, > struct page **pages) > { > struct mm_struct *mm = current->mm; > unsigned long addr, len, end; > unsigned long next; > - unsigned long flags; > pgd_t *pgdp; > int nr = 0; > > @@ -255,7 +260,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, > addr = start; > len = (unsigned long) nr_pages << PAGE_SHIFT; > end = start + len; > - if (unlikely(!access_ok(write ? VERIFY_WRITE : VERIFY_READ, > + if (unlikely(!access_ok((flags & GUPF_WRITE) ? VERIFY_WRITE : VERIFY_READ, > (void __user *)start, len))) > return 0; > > @@ -277,7 +282,6 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, > * (which we do on x86, with the above PAE exception), we can follow the > * address down to the the page and take a ref on it. > */ > - local_irq_save(flags); > pgdp = pgd_offset(mm, addr); > do { > pgd_t pgd = *pgdp; > @@ -285,14 +289,27 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, > next = pgd_addr_end(addr, end); > if (pgd_none(pgd)) > break; > - if (!gup_pud_range(pgd, addr, next, write, pages, &nr)) > + if (!gup_pud_range(pgd, addr, next, flags, pages, &nr)) > break; > } while (pgdp++, addr = next, addr != end); > - local_irq_restore(flags); > > return nr; > } > > +int __get_user_pages_fast(unsigned long start, int nr_pages, int write, > + struct page **pages) > +{ > + unsigned long flags; > + int ret; > + > + local_irq_save(flags); > + ret = ___get_user_pages_fast(start, nr_pages, > + GUPF_GET | (write ? GUPF_WRITE : 0), pages); > + local_irq_restore(flags); > + > + return ret; > +} > + > /** > * get_user_pages_fast() - pin user pages in memory > * @start: starting user address >