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Date: Wed, 4 Sep 2013 01:45:04 +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 Wed, Sep 4, 2013 at 12:37 AM, Sedat Dilek <sedat.dilek@...il.com> wrote: > 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.. >> >>> 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. >> > > [ init/Kconfig ] > ... > config TASKSTATS > bool "Export task/process statistics through netlink" > depends on NET <--- Difficult to disable it?! > default n > help > Export selected statistics for tasks/processes through the > generic netlink interface. Unlike BSD process accounting, the > statistics are available during the lifetime of tasks/processes as > responses to commands. Like BSD accounting, they are sent to user > space on task exit. > > Say N if unsure. > ... > So with Dave J.'s help I disabled CONFIG_TASKSTATS. But I still see that odd irq_ret* thing. My kernel-config and patch (on top of Linux v3.11) are attached. - Sedat - $ sudo ~/src/linux-kernel/linux/tools/perf/perf report -tui Samples: 161K of event 'cycles:pp', Event count (approx.): 76595555357 13,30%uit_lockref_from-ui[kernel.kallsyms] ui[k] irq_ret.rn 5,25%uit_lockref_from-ui[kernel.kallsyms] ui[k] lockref_get_or_lock 4,82%uit_lockref_from-ui[kernel.kallsyms] ui[k] __ticket_spin_lock 4,23%uit_lockref_from-ui[kernel.kallsyms] ui[k] .ser_exit 3,17%uit_lockref_from-ui[kernel.kallsyms] ui[k] local_clock 2,98%uit_lockref_from-ui[kernel.kallsyms] ui[k] kmem_cache_alloc 2,61%uit_lockref_from-uilibc-2.15.so ui[.] __xstat64 2,55%uit_lockref_from-ui[kernel.kallsyms] ui[k] link_path_walk 2,49%uit_lockref_from-ui[kernel.kallsyms] ui[k] kmem_cache_free 2,03%uit_lockref_from-ui[kernel.kallsyms] ui[k] tracesys 2,01%uit_lockref_from-ui[kernel.kallsyms] ui[k] path_look.pat 1,99%uit_lockref_from-ui[kernel.kallsyms] ui[k] rc._eqs_exit_common.isra.43 1,94%uit_lockref_from-ui[kernel.kallsyms] ui[k] .ser_enter 1,92%uit_lockref_from-ui[kernel.kallsyms] ui[k] rc._eqs_enter_common.isra.45 1,86%uit_lockref_from-ui[kernel.kallsyms] ui[k] sched_clock_cp. 1,72%uit_lockref_from-ui[kernel.kallsyms] ui[k] __d_look.p_rc. 1,71%uit_lockref_from-ui[kernel.kallsyms] ui[k] native_read_tsc 1,68%uit_lockref_from-ui[kernel.kallsyms] ui[k] cp_new_stat 1,65%uit_lockref_from-ui[kernel.kallsyms] ui[k] lockref_p.t_or_lock 1,64%uit_lockref_from-ui[kernel.kallsyms] ui[k] look.p_fast 1,59%uit_lockref_from-ui[kernel.kallsyms] ui[k] path_init 1,58%uit_lockref_from-ui[kernel.kallsyms] ui[k] native_sched_clock 1,57%uit_lockref_from-ui[kernel.kallsyms] ui[k] copy_.ser_generic_.nrolled 1,56%uit_lockref_from-ui[kernel.kallsyms] ui[k] syscall_trace_enter 1,53%uit_lockref_from-ui[kernel.kallsyms] ui[k] acco.nt_system_time 1,34%uit_lockref_from-ui[kernel.kallsyms] ui[k] getname_flags 1,28%uit_lockref_from-ui[kernel.kallsyms] ui[k] get_vtime_delta 1,26%uit_lockref_from-ui[kernel.kallsyms] ui[k] vfs_getattr 1,14%uit_lockref_from-ui[kernel.kallsyms] ui[k] syscall_trace_leave 1,11%uit_lockref_from-ui[kernel.kallsyms] ui[k] system_call 1,06%uit_lockref_from-ui[kernel.kallsyms] ui[k] strncpy_from_.ser 1,01%uit_lockref_from-ui[kernel.kallsyms] ui[k] generic_fillattr 0,97%uit_lockref_from-ui[kernel.kallsyms] ui[k] acco.nt_.ser_time 0,96%uit_lockref_from-ui[kernel.kallsyms] ui[k] .ser_path_at_empty 0,92%uit_lockref_from-ui[kernel.kallsyms] ui[k] filename_look.p 0,88%uit_lockref_from-ui[kernel.kallsyms] ui[k] __ticket_spin_.nlock 0,87%uit_lockref_from-ui[kernel.kallsyms] ui[k] complete_walk 0,86%uit_lockref_from-ui[kernel.kallsyms] ui[k] generic_permission 0,86%uit_lockref_from-ui[kernel.kallsyms] ui[k] common_perm 0,82%uit_lockref_from-ui[kernel.kallsyms] ui[k] vfs_fstatat 0,77%uit_lockref_from-ui[kernel.kallsyms] ui[k] rc._eqs_enter 0,75%uit_lockref_from-ui[kernel.kallsyms] ui[k] vtime_acco.nt_.ser 0,72%uit_lockref_from-ui[kernel.kallsyms] ui[k] __inode_permission 0,65%uit_lockref_from-ui[kernel.kallsyms] ui[k] dp.t 0,62%uit_lockref_from-ui[kernel.kallsyms] ui[k] vtime_.ser_enter 0,59%uit_lockref_from-ui[kernel.kallsyms] ui[k] apparmor_inode_getattr 0,55%uit_lockref_from-ui[kernel.kallsyms] ui[k] lg_local_lock 0,53%uit_lockref_from-ui[kernel.kallsyms] ui[k] __vtime_acco.nt_system 0,51%uit_lockref_from-ui[kernel.kallsyms] ui[k] sec.rity_inode_permission 0,51%uit_lockref_from-ui[kernel.kallsyms] ui[k] mntp.t 0,47%uit_lockref_from-uit_lockref_from-lin.sui[.] start_ro.tine 0,45%uit_lockref_from-ui[kernel.kallsyms] ui[k] cp.acct_acco.nt_field 0,45%uit_lockref_from-ui[kernel.kallsyms] ui[k] int_with_check 0,44%uit_lockref_from-ui[kernel.kallsyms] ui[k] rc._eqs_exit Press '?' for help on key bindings Download attachment "config-3.11.0-2-lockref-small" of type "application/octet-stream" (114160 bytes) Download attachment "3.11.0-2-lockref-small.patch" of type "application/octet-stream" (17163 bytes)
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