[Deepin-Kernel-SIG] [linux 6.6-y] [Upstream] ACPI: OSL: Use usleep_range() in acpi_os_sleep()

[opsiff]

mainline inclusion
from mainline-v6.14-rc1
category: bugfix

As stated by Len in [1], the extra delay added by msleep() to the sleep time value passed to it can be significant, roughly between 1.5 ns on systems with HZ = 1000 and as much as 15 ms on systems with HZ = 100, which is hardly acceptable, at least for small sleep time values.

msleep(5) on the default HZ = 250 in Ubuntu on a modern PC takes about 12 ms. This results in over 800 ms of spurious system resume delay on systems such as the Dell XPS-13-9300, which use ASL Sleep(5ms) in a tight loop.

Address this by using usleep_range() in acpi_os_sleep() instead of msleep(). For short sleep times this is a no brainer, but even for long sleeps usleep_range() should be preferred because timer wheel timers are optimized for cancelation before they expire and this particular timer is not going to be canceled.

Add at least 50 us on top of the requested sleep time in case the timer can be subject to coalescing, which is consistent with what's done in user space in this context [2], but for sleeps longer than 5 ms use 1% of the requested sleep time for this purpose.

The rationale here is that longer sleeps don't need that much of a timer precision as a rule and making the timer a more likely candidate for coalescing in these cases is generally desirable. It starts at 5 ms so that the delta between the requested sleep time and the effective deadline is a contiuous function of the former.

Link: https://lore.kernel.org/linux-pm/c7db7e804c453629c116d508558eaf46477a2d73.1731708405.git.len.brown@intel.com/ [1]
Link: https://lore.kernel.org/linux-pm/CAJvTdK=Q1kwWA6Wxn8Zcf0OicDEk6cHYFAvQVizgA47mXu63+g@mail.gmail.com/ [2]
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=216263
Reported-by: Len Brown [email protected]
Reviewed-by: Hans de Goede [email protected]
Reviewed-by: Mario Limonciello [email protected]
Tested-by: Mario Limonciello [email protected]

Link: https://patch.msgid.link/[email protected] (cherry picked from commit bede543)

Summary by Sourcery

Replace msleep() with usleep_range() in acpi_os_sleep() to avoid excessive delays, especially for short sleep times. This change improves system resume delays on certain systems. It also adds a delta to the sleep time to account for timer coalescing.

Bug Fixes:

• Reduces spurious system resume delay by using usleep_range() instead of msleep() in acpi_os_sleep().

Enhancements:

• Improves timer precision for short sleep times and increases the likelihood of timer coalescing for longer sleeps by adjusting the delta based on sleep duration.

[sourcery-ai]

Reviewer's Guide by Sourcery

This pull request replaces the usage of msleep with usleep_range in the acpi_os_sleep function. This change aims to provide more accurate sleep times and reduce delays during system resume. A delta is added to the sleep time to account for timer coalescing, with a minimum of 50us or 1% of the sleep time for longer sleeps.

No diagrams generated as the changes look simple and do not need a visual representation.

File-Level Changes

Change	Details	Files
Replaced msleep with usleep_range in acpi_os_sleep to improve sleep time accuracy and reduce spurious system resume delays.	Replaced msleep(ms) with a more precise implementation using usleep_range. Calculated the sleep time in microseconds. Added a delta to the sleep time to account for timer coalescing, using a minimum of 50us or 1% of the sleep time for sleeps longer than 5ms.	drivers/acpi/osl.c

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[sourcery-ai]

Hey @opsiff - I've reviewed your changes - here's some feedback:

Overall Comments:

• The commit message is very detailed, but consider if some of that detail belongs in the code as comments instead.

Here's what I looked at during the review

• 🟢 General issues: all looks good
• 🟢 Security: all looks good
• 🟢 Testing: all looks good
• 🟢 Complexity: all looks good
• 🟢 Documentation: all looks good

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