On Wed, Dec 14, 2011 at 4:27 PM, Daniel Lezcano <daniel.lezc...@linaro.org> wrote:
> while trying the linux-next at the point it boots (commit > be9b7335e70696bee731c152429b1737e42fe163, after v3.2-rc4), I noticed the > timers were not working properly with CONFIG_NO_HZ. > > It is easy to reproduce with 'time sleep 1' where the timer expires 1, 2 > or 3 seconds later. > > It seems that does not happen with linux-linaro-3.1 but I was able to > reproduce the problem on a vanilla kernel 3.1.5. > > Is it a known problem ? Sleeps are only guaranteed at max speed. Since this is jiffy-based sleep I think these patches (which I just updated and put into Russell's patch tracker) are needed: http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=7210/1 http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=7211/1 http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=7212/1 If these patches solve your issue please ACK them on the linux-arm-kernel maillist, so Russell et al can see that they solve problems for people... You will then encounter the same problem at the udelay(), mdelay() etc to which these patches provide a solution (with an additional ux500 MTU patch that is somewhere in our tree): http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=6873/1 http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=6874/1 http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=6875/1 Linus Walleij _______________________________________________ linaro-dev mailing list linaro-dev@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-dev
