svn commit: r363125 - head/sys/compat/linux

[Alexander Leidinger]

Author: netchild
Date: Sun Jul 12 09:51:09 2020
New Revision: 363125
URL: https://svnweb.freebsd.org/changeset/base/363125

Log:
  Implement CLOCK_MONOTONIC_RAW (linux >= 2.6.28).
  
  It is documented as a raw hardware-based clock not subject to NTP or
  incremental adjustments. With this "not as precise as CLOCK_MONOTONIC"
  description in mind, map it to our CLOCK_MONOTNIC_FAST (the same
  mapping as for the linux CLOCK_MONOTONIC_COARSE).
  
  This is needed for the webcomponent of steam (chromium) and some
  other steam component or game.
  
  The linux-steam-utils port contains a LD_PRELOAD based fix for this.
  There this is mapped to CLOCK_MONOTONIC.
  As an untrained ear/eye (= the majority of people) is normaly not
  noticing a difference of jitter in the 10-20 ms range, specially
  if you don't pay attention like for example in a browser session
  while watching a video stream, the mapping to CLOCK_MONOTONIC_FAST
  seems more appropriate than to CLOCK_MONOTONIC.

Modified:
  head/sys/compat/linux/linux_time.c

Modified: head/sys/compat/linux/linux_time.c
==============================================================================
--- head/sys/compat/linux/linux_time.c	Sun Jul 12 09:49:53 2020	(r363124)
+++ head/sys/compat/linux/linux_time.c	Sun Jul 12 09:51:09 2020	(r363125)
@@ -212,6 +212,7 @@ linux_to_native_clockid(clockid_t *n, clockid_t l)
 		*n = CLOCK_THREAD_CPUTIME_ID;
 		break;
 	case LINUX_CLOCK_REALTIME_COARSE:
+	case LINUX_CLOCK_MONOTONIC_RAW:
 		*n = CLOCK_REALTIME_FAST;
 		break;
 	case LINUX_CLOCK_MONOTONIC_COARSE:
@@ -220,7 +221,6 @@ linux_to_native_clockid(clockid_t *n, clockid_t l)
 	case LINUX_CLOCK_BOOTTIME:
 		*n = CLOCK_UPTIME;
 		break;
-	case LINUX_CLOCK_MONOTONIC_RAW:
 	case LINUX_CLOCK_REALTIME_ALARM:
 	case LINUX_CLOCK_BOOTTIME_ALARM:
 	case LINUX_CLOCK_SGI_CYCLE: