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Message-ID: <CA+icZUWPUDorK+9KRD-H3FpbDeC_7LMatzrYk35jZk13vNuLBQ@mail.gmail.com> Date: Sun, 1 Sep 2013 17:45:03 +0200 From: Sedat Dilek <sedat.dilek@...il.com> To: Linus Torvalds <torvalds@...ux-foundation.org> Cc: Waiman Long <waiman.long@...com>, Ingo Molnar <mingo@...nel.org>, Benjamin Herrenschmidt <benh@...nel.crashing.org>, Alexander Viro <viro@...iv.linux.org.uk>, Jeff Layton <jlayton@...hat.com>, Miklos Szeredi <mszeredi@...e.cz>, Ingo Molnar <mingo@...hat.com>, Thomas Gleixner <tglx@...utronix.de>, linux-fsdevel <linux-fsdevel@...r.kernel.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Peter Zijlstra <peterz@...radead.org>, Steven Rostedt <rostedt@...dmis.org>, Andi Kleen <andi@...stfloor.org>, "Chandramouleeswaran, Aswin" <aswin@...com>, "Norton, Scott J" <scott.norton@...com> Subject: Re: [PATCH v7 1/4] spinlock: A new lockref structure for lockless update of refcount On Sun, Sep 1, 2013 at 5:32 PM, Linus Torvalds <torvalds@...ux-foundation.org> wrote: > On Sun, Sep 1, 2013 at 3:01 AM, Sedat Dilek <sedat.dilek@...il.com> wrote: >> >> Looks like this is now 10x faster: ~2.66Mloops (debug) VS. >> ~26.60Mloops (no-debug). > > Ok, that's getting to be in the right ballpark. > > But your profile is still odd. > >> Samples: 159K of event 'cycles:pp', Event count (approx.): 76968896763 >> 12,79% t_lockref_from- [kernel.kallsyms] [k] irq_return >> 4,36% t_lockref_from- [kernel.kallsyms] [k] __ticket_spin_lock > > If you do the profile with "-g", what are the top callers of this? You > shouldn't see any spinlock load from the path lookup, but you have all > these other things going on.. > $ sudo ~/src/linux-kernel/linux/tools/perf/perf record -g -e cycles:pp ./scripts/t_lockref_from-linus Total loops: 26205085 [ perf record: Woken up 77 times to write data ] [ perf record: Captured and wrote 19.778 MB perf.data (~864092 samples) ] $ sudo ~/src/linux-kernel/linux/tools/perf/perf report <--- I used here with -f option, the last one, dropped here. Samples: 160K of event 'cycles:pp', Event count (approx.): 77003901089 + 12,46% t_lockref_from- [kernel.kallsyms] [k] irq_return + 4,86% t_lockref_from- [kernel.kallsyms] [k] lockref_get_or_lock + 4,42% t_lockref_from- [kernel.kallsyms] [k] __ticket_spin_lock + 4,28% t_lockref_from- [kernel.kallsyms] [k] __acct_update_integrals + 3,97% t_lockref_from- [kernel.kallsyms] [k] user_exit + 3,04% t_lockref_from- [kernel.kallsyms] [k] local_clock + 2,71% t_lockref_from- [kernel.kallsyms] [k] kmem_cache_alloc + 2,50% t_lockref_from- [kernel.kallsyms] [k] link_path_walk + 2,46% t_lockref_from- libc-2.15.so [.] __xstat64 + 2,38% t_lockref_from- [kernel.kallsyms] [k] kmem_cache_free + 1,96% t_lockref_from- [kernel.kallsyms] [k] path_lookupat + 1,88% t_lockref_from- [kernel.kallsyms] [k] __d_lookup_rcu + 1,87% t_lockref_from- [kernel.kallsyms] [k] tracesys + 1,84% t_lockref_from- [kernel.kallsyms] [k] rcu_eqs_exit_common.isra.43 + 1,81% t_lockref_from- [kernel.kallsyms] [k] rcu_eqs_enter_common.isra.45 + 1,80% t_lockref_from- [kernel.kallsyms] [k] user_enter + 1,79% t_lockref_from- [kernel.kallsyms] [k] sched_clock_cpu + 1,61% t_lockref_from- [kernel.kallsyms] [k] native_read_tsc + 1,56% t_lockref_from- [kernel.kallsyms] [k] cp_new_stat + 1,52% t_lockref_from- [kernel.kallsyms] [k] lockref_put_or_lock + 1,51% t_lockref_from- [kernel.kallsyms] [k] account_system_time + 1,46% t_lockref_from- [kernel.kallsyms] [k] path_init + 1,46% t_lockref_from- [kernel.kallsyms] [k] copy_user_generic_unrolled + 1,42% t_lockref_from- [kernel.kallsyms] [k] syscall_trace_enter + 1,38% t_lockref_from- [kernel.kallsyms] [k] jiffies_to_timeval + 1,32% t_lockref_from- [kernel.kallsyms] [k] lookup_fast + 1,31% t_lockref_from- [kernel.kallsyms] [k] native_sched_clock + 1,24% t_lockref_from- [kernel.kallsyms] [k] getname_flags + 1,17% t_lockref_from- [kernel.kallsyms] [k] vfs_getattr + 1,15% t_lockref_from- [kernel.kallsyms] [k] get_vtime_delta + 1,03% t_lockref_from- [kernel.kallsyms] [k] syscall_trace_leave + 0,95% t_lockref_from- [kernel.kallsyms] [k] generic_fillattr + 0,94% t_lockref_from- [kernel.kallsyms] [k] user_path_at_empty + 0,93% t_lockref_from- [kernel.kallsyms] [k] system_call_after_swapgs + 0,93% t_lockref_from- [kernel.kallsyms] [k] account_user_time + 0,89% t_lockref_from- [kernel.kallsyms] [k] strncpy_from_user + 0,86% t_lockref_from- [kernel.kallsyms] [k] complete_walk + 0,80% t_lockref_from- [kernel.kallsyms] [k] filename_lookup + 0,80% t_lockref_from- [kernel.kallsyms] [k] vfs_fstatat + 0,78% t_lockref_from- [kernel.kallsyms] [k] generic_permission + 0,77% t_lockref_from- [kernel.kallsyms] [k] __ticket_spin_unlock + 0,73% t_lockref_from- [kernel.kallsyms] [k] __inode_permission + 0,69% t_lockref_from- [kernel.kallsyms] [k] vtime_account_user + 0,66% t_lockref_from- [kernel.kallsyms] [k] d_rcu_to_refcount + 0,61% t_lockref_from- [kernel.kallsyms] [k] common_perm + 0,60% t_lockref_from- [kernel.kallsyms] [k] rcu_eqs_enter + 0,59% t_lockref_from- [kernel.kallsyms] [k] dput + 0,54% t_lockref_from- [kernel.kallsyms] [k] vtime_user_enter + 0,51% t_lockref_from- [kernel.kallsyms] [k] cpuacct_account_field + 0,50% t_lockref_from- [kernel.kallsyms] [k] mntput + 0,48% t_lockref_from- [kernel.kallsyms] [k] lg_local_lock + 0,48% t_lockref_from- [kernel.kallsyms] [k] apparmor_inode_getattr + 0,45% t_lockref_from- t_lockref_from-linus [.] start_routine + 0,45% t_lockref_from- [kernel.kallsyms] [k] __vtime_account_system Press '?' for help on key bindings - Sedat - >> 4,36% t_lockref_from- [kernel.kallsyms] [k] __acct_update_integrals >> 4,07% t_lockref_from- [kernel.kallsyms] [k] user_exit >> 3,12% t_lockref_from- [kernel.kallsyms] [k] local_clock >> 2,83% t_lockref_from- [kernel.kallsyms] [k] lockref_get_or_lock >> 2,73% t_lockref_from- [kernel.kallsyms] [k] kmem_cache_alloc >> 2,62% t_lockref_from- [kernel.kallsyms] [k] __d_lookup_rcu > > You're spending more time on the task stats than on the actual lookup. > Maybe you should turn off CONFIG_TASKSTATS..But why that whole > irq_return thing? Odd. > Yes, I have CONFIG_TASKSTATS=y. I can try a -4 build w/o it. - Sedat - -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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