[lkml]   [2005]   [Dec]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH 1/12]: MUTEX: Implement mutexes
On Sat, 17 Dec 2005, Linus Torvalds wrote:

> Of the other architectures you list, only ARM is really important. And no,
> arm doesn't do swap. It does LL/SC (except they call it "ldrex/strex",
> which I assume stands for "load/store with reservation and X just because
> X is cool. Yeah, we're cool" (*)).

Well, if you really want to be honest, you have to consider that the
ldrex/strex instructions are available only on ARM architecture level 6
and above, or in other words with only about 1% of all ARM deployments
out there. The other 99% of actual ARM processors in the field only
have the atomic swap (swp) instruction which is insufficient for
implementing a counting semaphore (we therefore have to disable
interrupts, do the semaphore update and enable interrupts again which is
much slower than a swp-based mutex).

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-12-18 02:32    [W:0.074 / U:1.584 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site