On Wed, Mar 15, 2017 at 09:51:47PM +0530, Nayna wrote: > > > On 03/15/2017 09:22 PM, Jarkko Sakkinen wrote: > > On Fri, Mar 10, 2017 at 01:45:53PM -0500, Nayna Jain wrote: > > > Commit 500462a9de65 "timers: Switch to a non-cascading wheel" replaced > > > the 'classic' timer wheel, which aimed for near 'exact' expiry of the > > > timers. Their analysis was that the vast majority of timeout timers > > > are used as safeguards, not as real timers, and are cancelled or > > > rearmed before expiration. The only exception noted to this were > > > networking timers with a small expiry time. > > > > > > Not included in the analysis was the TPM polling timer, which resulted > > > in a longer normal delay and, every so often, a very long delay. The > > > non-cascading wheel delay is based on CONFIG_HZ. For a description of > > > the different rings and their delays, refer to the comments in > > > kernel/time/timer.c. > > > > > > Below are the delays given for rings 0 - 2, which explains the longer > > > "normal" delays and the very, long delays as seen on systems with > > > CONFIG_HZ 250. > > > > > > * HZ 1000 steps > > > * Level Offset Granularity Range > > > * 0 0 1 ms 0 ms - 63 ms > > > * 1 64 8 ms 64 ms - 511 ms > > > * 2 128 64 ms 512 ms - 4095 ms (512ms - ~4s) > > > > > > * HZ 250 > > > * Level Offset Granularity Range > > > * 0 0 4 ms 0 ms - 255 ms > > > * 1 64 32 ms 256 ms - 2047 ms (256ms - ~2s) > > > * 2 128 256 ms 2048 ms - 16383 ms (~2s - ~16s) > > > > > > Below is a comparison of extending the TPM with 1000 measurements, > > > using msleep() vs. usleep_delay() when configured for 1000 hz vs. 250 > > > hz, before and after commit 500462a9de65. > > > > > > linux-4.7 | msleep() usleep_range() > > > 1000 hz: 0m44.628s | 1m34.497s 29.243s > > > 250 hz: 1m28.510s | 4m49.269s 32.386s > > > > > > linux-4.7 | min-max (msleep) min-max (usleep_range) > > > 1000 hz: 0:017 - 2:760s | 0:015 - 3:967s 0:014 - 0:418s > > > 250 hz: 0:028 - 1:954s | 0:040 - 4:096s 0:016 - 0:816s > > > > > > This patch replaces the msleep() with usleep_range() calls in the > > > i2c nuvoton driver with a consistent max range value. > > > > > > Signed-of-by: Mimi Zohar <zo...@linux.vnet.ibm.com> > > > Cc: sta...@vger.kernel.org (linux-4.8) > > > Signed-off-by: Nayna Jain <na...@linux.vnet.ibm.com> > > > --- > > > Changelog v1: > > > > > > - Included Jason's feedbacks related to #defines. > > > > What was changed? > > > > Changelog v1: > >> > >> - Included Jason's feedbacks related to #defines. > > Based on Jason's review: > - Added () in #define > - Replaced hardcoded maximum range value with defined name. > > Hmm.. could have included exact details. > > Thanks & Regards, > - Nayna > > > /Jarkko > >
OK, I'll replace the original patch with this. Thanks. /Jarkko
