On Wed, Feb 07, 2018 at 01:26:19PM -0500, Steven Rostedt wrote: > On Wed, 7 Feb 2018 10:10:55 -0800 > Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: > > > > For the record, I fully agree with Steve here. > > Thanks, but... > > > > > > > And being a performance "fanatic" I don't like to have the extra branch > > > (and compares) in the free code path... but it's a MM-decision (and > > > sometimes you should not listen to "fanatics" ;-)) > > > > While free_rcu() is not withut its performance requirements, I think it's > > currently dominated by cache misses and not by branches. By the time RCU > > gets to run callbacks, memory is certainly L1/L2 cache-cold and probably > > L3 cache-cold. Also calling the callback functions is utterly impossible > > for the branch predictor. > > I agree with Matthew. > > This is far from any fast path. A few extra branches isn't going to > hurt anything here as it's mostly just garbage collection. With or > without the Spectre fixes. What Steve said! Thanx, Paul -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
