On Fri, Apr 15, 2011 at 19:11, Rafael J. Wysocki wrote: > On Friday, April 15, 2011, Mike Frysinger wrote: >> On Fri, Apr 15, 2011 at 12:29, Pavel Machek wrote: >> >> > > I believe the code is correct as is. >> >> > >> >> > that isnt what the code / documentation says. Âunless i'm reading them >> >> > wrong, both seem to indicate that the proposed patch is what we >> >> > actually want. >> >> >> >> The existing code is correct but it isn't optimal. >> >> >> >> wmb() and rmb() are heavy-duty operations, and you don't want to call >> >> them when they aren't needed. ÂThat's exactly what smp_wmb() and >> >> smp_rmb() are for -- they call wmb() and rmb(), but only in SMP >> >> kernels. >> >> >> >> Unless you need to synchronize with another processor (not necessarily >> >> a CPU, it could be something embedded within a device), you should >> >> always use smp_wmb() and smp_rmb() rather than wmb() and rmb(). >> > >> > Maybe; but this code is not performance critical and I believe being >> > obvious here is better... >> >> isnt it though ? Âespecially when we talk about suspending/resuming on >> embedded systems to get more savings over just cpu idle ? Âwe want >> that latency to be as low as possible. > > I agree, we can switch the freezer to smp_ barriers, but not for the reason > you gave before. :-) > > Care to repost the patch with a suitable changelog? np to be clear, what you said wrt the Blackfin smp barriers still holds true right ? so this changset i merged doesnt need any tweaking ... http://git.kernel.org/?p=linux/kernel/git/vapier/blackfin.git;a=commitdiff;h=943aee0c685d0563228d5a2ad9c8394ad0300fb5 -mike _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
