-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 12/14/2011 05:02 PM, Linus Walleij wrote: > 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.
I am not sure to get the point. Do you mean cpufreq max frequency ? > 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 These three patches do not solve the problem. > 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 I tried to apply these patches on linux-next (again at the point the snowball boots), but they don't apply. They are trying to modify arch/arm/lib/delay.c which does not exist in the current commit neither in the HEAD. Isn't there a patch to be applied before ? By the way, while reading the description of the patches, I tested with an UP kernel instead of SMP and the problem does not appear. I tried again with a SMP kernel but unplugging cpu1 and the problem is still there. Hope that helps. -- Daniel Thanks -- Daniel - -- <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | <http://twitter.com/#!/linaroorg> Twitter | <http://www.linaro.org/linaro-blog/> Blog -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iQEcBAEBAgAGBQJO6eUZAAoJEAKBbMCpUGYA5jIIAMSXynp9H5/5cygRh9hJ6HN3 IY4x49rfPJXKEw5JQQ5ydfJtavgWvxm2z6+oZoh1bSwaw2cvoKPHfZpok3sKT3H9 JneTkMY818T3PLkZYbK4sfnFkJqIyP+jajygpnYJNYThqEsXijGLg48DNd8xVhDm ZnuiTs2/KnX4nMKTaJacI8VS16SlQ8PUcYuAm74LUbT3OfhW3IUe1heezvuTZvFH lQBP+uvBvF4bdulolha2Q8Id0ON7ATl/zE0yRds60z0lpcgle8yB9AU69IXrTOih XcgL1XC5A64U2waMPztj0lcLvd71PZAhuV1RtIfLSZqzAoracugyET93vCWbnAc= =zpkA -----END PGP SIGNATURE----- _______________________________________________ linaro-dev mailing list linaro-dev@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-dev
