From: Byungchul Park <max.byungchul.park@gmail.com>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Byungchul Park <byungchul.park@lge.com>,
peterz@infradead.org, Ingo Molnar <mingo@kernel.org>,
tglx@linutronix.de, walken@google.com, boqun.feng@gmail.com,
kirill@shutemov.name,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org, iamjoonsoo.kim@lge.com,
akpm@linux-foundation.org, npiggin@gmail.com
Subject: Re: [PATCH v3 01/15] x86/dumpstack: Optimize save_stack_trace
Date: Tue, 13 Sep 2016 23:54:17 +0900 [thread overview]
Message-ID: <CANrsvRMvk_SdaqN-8cr4VJNd=CCrGv__36KwcpdjTUczm=Y0nA@mail.gmail.com> (raw)
In-Reply-To: <20160913131802.oiwxgpmccn7uufef@treble>
On Tue, Sep 13, 2016 at 10:18 PM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> On Tue, Sep 13, 2016 at 06:45:00PM +0900, Byungchul Park wrote:
>> Currently, x86 implementation of save_stack_trace() is walking all stack
>> region word by word regardless of what the trace->max_entries is.
>> However, it's unnecessary to walk after already fulfilling caller's
>> requirement, say, if trace->nr_entries >= trace->max_entries is true.
>>
>> I measured its overhead and printed its difference of sched_clock() with
>> my QEMU x86 machine. The latency was improved over 70% when
>> trace->max_entries = 5.
>
> This code will (probably) be obsoleted soon with my new unwinder.
Hello,
You are right.
I also think this will probably be obsoleted with yours.
So I didn't modify any details of the patch.
I will take your comment into account if it becomes necessary.
Anyway, crossrelease needs this patch to work smoothly.
That's only reason why I included this patch in the thread.
Thank you,
Byungchul
> Also, my previous comment was ignored:
>
> Instead of adding a new callback, why not just check the ops->address()
> return value? It already returns an error if the array is full.
>
> I think that would be cleaner and would help prevent more callback
> sprawl.
>
> --
> Josh
--
Thanks,
Byungchul
next prev parent reply other threads:[~2016-09-13 14:54 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-13 9:44 [PATCH v3 00/15] lockdep: Implement crossrelease feature Byungchul Park
2016-09-13 9:45 ` [PATCH v3 01/15] x86/dumpstack: Optimize save_stack_trace Byungchul Park
2016-09-13 13:18 ` Josh Poimboeuf
2016-09-13 14:54 ` Byungchul Park [this message]
2016-09-13 9:45 ` [PATCH v3 02/15] x86/dumpstack: Add save_stack_trace()_fast() Byungchul Park
2016-09-13 13:20 ` Josh Poimboeuf
2016-09-13 9:45 ` [PATCH v3 03/15] lockdep: Refactor lookup_chain_cache() Byungchul Park
2016-09-15 15:33 ` Nilay Vaish
2016-09-19 3:05 ` Byungchul Park
2016-09-19 16:36 ` Nilay Vaish
2016-09-20 2:00 ` Byungchul Park
2016-09-13 9:45 ` [PATCH v3 04/15] lockdep: Add a function building a chain between two classes Byungchul Park
2016-09-13 9:45 ` [PATCH v3 05/15] lockdep: Make check_prev_add can use a separate stack_trace Byungchul Park
2016-09-13 9:45 ` [PATCH v3 06/15] lockdep: Make save_trace can skip stack tracing of the current Byungchul Park
2016-09-13 9:45 ` [PATCH v3 07/15] lockdep: Implement crossrelease feature Byungchul Park
2016-09-13 10:05 ` Peter Zijlstra
2016-09-13 12:09 ` Peter Zijlstra
2016-09-13 15:14 ` Byungchul Park
2016-09-13 15:05 ` Peter Zijlstra
2016-09-13 17:12 ` Byungchul Park
2016-09-13 19:38 ` Peter Zijlstra
2016-09-13 21:42 ` Peter Zijlstra
2016-09-14 1:01 ` Byungchul Park
2016-09-14 2:27 ` Byungchul Park
2016-09-14 4:49 ` Byungchul Park
2016-09-14 8:11 ` Peter Zijlstra
2016-09-19 2:41 ` Byungchul Park
2016-09-19 8:50 ` Peter Zijlstra
2016-09-20 5:50 ` Byungchul Park
2016-09-20 6:26 ` Byungchul Park
2016-09-21 1:37 ` Byungchul Park
2016-09-22 2:57 ` Byungchul Park
2016-09-13 9:45 ` [PATCH v3 08/15] lockdep: Make crossrelease use save_stack_trace_fast() Byungchul Park
2016-09-13 9:45 ` [PATCH v3 09/15] lockdep: Make print_circular_bug() crosslock-aware Byungchul Park
2016-09-13 9:45 ` [PATCH v3 10/15] lockdep: Apply crossrelease to completion operation Byungchul Park
2016-09-13 9:45 ` [PATCH v3 11/15] pagemap.h: Remove trailing white space Byungchul Park
2016-09-13 9:45 ` [PATCH v3 12/15] lockdep: Apply crossrelease to PG_locked lock Byungchul Park
2016-09-13 9:45 ` [PATCH v3 13/15] lockdep: Apply lock_acquire(release) on __Set(__Clear)PageLocked Byungchul Park
2016-09-13 9:45 ` [PATCH v3 14/15] lockdep: Move data used in CONFIG_LOCKDEP_PAGELOCK from page to page_ext Byungchul Park
2016-09-13 9:45 ` [PATCH v3 15/15] lockdep: Crossrelease feature documentation Byungchul Park
2016-09-15 17:25 ` Nilay Vaish
2016-09-19 2:59 ` Byungchul Park
2016-09-16 15:47 ` Nilay Vaish
2016-09-19 3:00 ` Byungchul Park
2016-09-20 5:00 ` Byungchul Park
2016-09-13 9:58 ` [FYI] Output of 'cat /proc/lockdep' after applying crossrelease Byungchul Park
2016-11-02 5:42 ` [REVISED DOC on v3] Crossrelease Lockdep Byungchul Park
2016-11-03 8:18 ` Byungchul Park
2016-11-08 2:54 ` Byungchul Park
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