Messages in this thread | | | Subject | Re: [PATCH v1 1/2] tpm: msleep() delays - replace with usleep_range() in i2c nuvoton driver | From | Nayna <> | Date | Wed, 15 Mar 2017 21:51:47 +0530 |
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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 <zohar@linux.vnet.ibm.com> >> Cc: stable@vger.kernel.org (linux-4.8) >> Signed-off-by: Nayna Jain <nayna@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 >
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