On Thu, Jan 10, 2008 at 11:57:26AM +0100, Ingo Molnar wrote:Cached requires the cache line to be read first before you can write it. WC on the other hand does not allocate a cache line and just dumps the data into a special write combining buffer. It was invented originally because reads from AGP were incredibly slow. And it's race less regarding the caching protocol (assuming you flush the caches and TLBs correctly). Another typical problem is that if something is uncached then you can't have it in any other caches because if that cache eventually flushes it will corrupt the data. That can happen with remapping apertures for example which remap data behind the CPUs back. CLFLUSH is really only a hint but it cannot be used if UC is needed for correctness. The typical case would be lots of user space DRI clients supplying their own buffers on the fly. There's not really a fixed pool in this case, but it all varies dynamically. In some scenarios that could happen quite often. -Andi --
| Greg KH | Og dreams of kernels |
| Jens Axboe | [PATCH 31/33] Fusion: sg chaining support |
| Arnd Bergmann | Re: finding your own dead "CONFIG_" variables |
| Mark Brown | [PATCH 2/2] Subject: natsemi: Allow users to disable workaround for DspCfg reset |
| Tony Breeds | [LGUEST] Look in object dir for .config |
git: | |
| Brian Downing | Re: Git in a Nutshell guide |
| John Benes | Re: master has some toys |
| Matthias Lederhofer | [PATCH 4/7] introduce GIT_WORK_TREE to specify the work tree |
| Alexander Sulfrian | [RFC/PATCH] RE: git calls SSH_ASKPASS even if DISPLAY is not set |
| Junio C Hamano |
