Messages in this thread |  | | Date | Tue, 16 Apr 1996 14:55:44 +0200 (MET DST) | From | Ingo Molnar <> | Subject | Re: 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(
|  |