[lkml]   [2010]   [May]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: Perf and ftrace [was Re: PyTimechart]
On Wed, 2010-05-12 at 13:07 -0400, Mathieu Desnoyers wrote:
> > Its mostly an interface/api question. You cannot easily splice() a
> > mmap()'ed buffer on machines that have address constraints like sparc.
> Ah ? Can you explain this issue a bit more ? There is possibly a concern I don't
> quite see here.

IIRC Sparc has virtually tagged D-caches on the lower 9 bits of the pfn,
so to avoid cache aliasing both mappings (kernel and user) need to be

Since splice needs to swap pages it needs to allocate replacement pages
with the exact right alignment, which is rather expensive (in either
time or space).

 \ /
  Last update: 2010-05-12 19:49    [W:0.097 / U:17.616 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site