lkml.org 
[lkml]   [1996]   [Apr]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Ideas for reducing memory copying and zeroing times
On Tue, 16 Apr 1996, Werner Almesberger wrote:

> See http://lrcwww.epfl.ch/linux-atm/ for the general picture.
>
> What's different is that I don't have a zero page cache (no SMP ;-), but
> I like that idea), and that I keep write buffers simply locked instead of
> giving them to the kernel. To improve the latter, my (untested) free_range
> function could be used in operations that are guaranteed to discard all
> previous contents (e.g. in read system calls), but I haven't experimented
> with that bit yet.

havent checked out your source yet, but under AIX similar approach is
used for async IO. Under Linux, if processes that get clone()-d with
VM_SHARE, and run on another CPU (or even the same if the socket
operation sleeps) and use the same page(s) which are locked, then we
might get problems. If there is a local variable right in the same page as
your IO buffer, doesnt this cause problems or unnecessary/unexpected sleeps?

well, on the x86, maybe segments with 1 byte granularity could be used
to cut off user-space IO buffers, but this is ugly, isnt it

-- mingo, who likes the idea of zero copy, but still doesnt see how it
could be done cleanly 8(


\
 
 \ /
  Last update: 2005-03-22 13:37    [W:1.148 / U:0.004 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site