On 1/10/25 11:00, Mark Johnston wrote:
The branch main has been updated by markj:
URL:
https://cgit.FreeBSD.org/src/commit/?id=6b82130e6c9add4a8892ca897df5a0ec04663ea2
commit 6b82130e6c9add4a8892ca897df5a0ec04663ea2
Author: Mark Johnston <ma...@freebsd.org>
AuthorDate: 2025-01-10 15:37:07 +0000
Commit: Mark Johnston <ma...@freebsd.org>
CommitDate: 2025-01-10 15:42:59 +0000
clock: Add a long ticks variable, ticksl
For compatibility with Linux, it's useful to have a tick counter of
width sizeof(long), but our tick counter is an int. Currently the
linuxkpi tries paper over this difference, but this cannot really be
done reliably, so it's desirable to have a wider tick counter. This
change introduces ticksl, keeping the existing ticks variable.
Follow a suggestion from kib to avoid having to maintain two separate
counters and to avoid converting existing code to use ticksl: change
hardclock() to update ticksl instead of ticks, and then use assembler
directives to make ticks and ticksl overlap such that loading ticks
gives the bottom 32 bits. This makes it possible to use ticksl in the
linuxkpi without having to convert any native code, and without making
hardclock() more complicated or expensive. Then, the linuxkpi can be
modified to use ticksl instead of ticks.
Reviewed by: olce, kib, emaste
MFC after: 1 month
Differential Revision: https://reviews.freebsd.org/D48383
---
sys/conf/files | 1 +
sys/kern/kern_clock.c | 26 ++++++++++++++------------
sys/kern/kern_tc.c | 4 ++--
sys/kern/subr_param.c | 2 +-
sys/kern/subr_ticks.s | 44 ++++++++++++++++++++++++++++++++++++++++++++
sys/sys/kernel.h | 9 +++++++++
sys/sys/timetc.h | 2 +-
7 files changed, 72 insertions(+), 16 deletions(-)
diff --git a/sys/kern/subr_param.c b/sys/kern/subr_param.c
index 19169ba63061..f4359efec466 100644
--- a/sys/kern/subr_param.c
+++ b/sys/kern/subr_param.c
@@ -197,7 +197,7 @@ init_param1(void)
* Arrange for ticks to wrap 10 minutes after boot to help catch
* sign problems sooner.
*/
- ticks = INT_MAX - (hz * 10 * 60);
+ ticksl = INT_MAX - (hz * 10 * 60);
vn_lock_pair_pause_max = hz / 100;
if (vn_lock_pair_pause_max == 0)
Did you consider using LONG_MAX here instead of INT_MAX? That would make
both values roll over 10 minutes after boot so that sign problems can be
tested for both counters.
--
John Baldwin
