lkml.org 
[lkml]   [2016]   [Sep]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v3 01/15] x86/dumpstack: Optimize save_stack_trace
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.

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

\
 
 \ /
  Last update: 2016-09-17 09:59    [W:0.265 / U:2.780 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site