Messages in this thread |  | | | Date | Fri, 7 Jan 2011 00:32:41 -0800 | | From | "Paul E. McKenney" <> | | Subject | Re: [GIT PULL] RCU changes for v2.6.38 |
| |
On Fri, Jan 07, 2011 at 12:54:57AM +0100, Ingo Molnar wrote: > > * Linus Torvalds <torvalds@linux-foundation.org> wrote: > > > On Thu, Jan 6, 2011 at 1:08 AM, Ingo Molnar <mingo@elte.hu> wrote: > > > > > > Please pull the latest core-rcu-for-linus git tree from: > > > > So I pulled, but I'm not convinced about the crazy busy-looping > > SRCU_SYNCHRONIZE_DELAY thing. > > > > Why does it do a silly udelay(), instead of just looping over the > > srcu_readers_active_idx() for a few times? You're wasting CPU time > > anyway, why ask the user how many usecs to waste? > > > > IOW, why isn't that "wait for no active readers" a nice helper > > function, and why doesn't it do > > > > for (i = 0; i < CONFIG_SRCU_SYNCHRONIZE_DELAY; i++) { > > if (!srcu_readers_active_idx(sp, idx)) > > return; > > udelay(1); > > } > > while (srcu_readers_active_idx(sp, idx)) > > schedule_timeout_interruptible(1); > > > > instead? And is it really sane to ask the kernel configurator to come > > up with a random value (ie that "CONFIG_SRCU_SYNCHRONIZE_DELAY" is > > just stupid and wrong)? > > > > Please fix this. And don't make people answer unanswerable questions. > > If YOU and Paul don't know the answer, why the hell do you expect > > somebody who does a "make config" to know the answer? > > > > Either pick a number, or pick an algorithm that self-tunes. > > > > Don't use the Kconfig system as a way to tell people that it's their > > fault when you made a bad decision. Really. > > Fully agreed - we'll fix this.
I am on it!
Thanx, Paul
|  |