git: ee29897fc3d6 - main - time(3): Declare the minimum and maximum hz values supported.
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Date: Sun, 23 Oct 2022 08:14:18 UTC
The branch main has been updated by hselasky: URL: https://cgit.FreeBSD.org/src/commit/?id=ee29897fc3d66ba7006c9ee3f524bf2e8cf30a4f commit ee29897fc3d66ba7006c9ee3f524bf2e8cf30a4f Author: Hans Petter Selasky <hselasky@FreeBSD.org> AuthorDate: 2022-10-03 09:08:53 +0000 Commit: Hans Petter Selasky <hselasky@FreeBSD.org> CommitDate: 2022-10-23 08:04:50 +0000 time(3): Declare the minimum and maximum hz values supported. Reviewed by: kib@ and imp@ MFC after: 1 week Sponsored by: NVIDIA Networking Differential Revision: https://reviews.freebsd.org/D37072 --- sys/kern/subr_param.c | 11 +++++++++++ sys/sys/time.h | 7 +++++++ 2 files changed, 18 insertions(+) diff --git a/sys/kern/subr_param.c b/sys/kern/subr_param.c index ebb21283c5f9..f9c2f8df87b8 100644 --- a/sys/kern/subr_param.c +++ b/sys/kern/subr_param.c @@ -111,6 +111,10 @@ u_long sgrowsiz; /* amount to grow stack */ SYSCTL_INT(_kern, OID_AUTO, hz, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &hz, 0, "Number of clock ticks per second"); +SYSCTL_INT(_kern, OID_AUTO, hz_max, CTLFLAG_RD, SYSCTL_NULL_INT_PTR, HZ_MAXIMUM, + "Maximum hz value supported"); +SYSCTL_INT(_kern, OID_AUTO, hz_min, CTLFLAG_RD, SYSCTL_NULL_INT_PTR, HZ_MINIMUM, + "Minimum hz value supported"); SYSCTL_INT(_kern, OID_AUTO, nbuf, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &nbuf, 0, "Number of buffers in the buffer cache"); SYSCTL_INT(_kern, OID_AUTO, nswbuf, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &nswbuf, 0, @@ -173,6 +177,13 @@ init_param1(void) TUNABLE_INT_FETCH("kern.hz", &hz); if (hz == -1) hz = vm_guest > VM_GUEST_NO ? HZ_VM : HZ; + + /* range check the "hz" value */ + if (__predict_false(hz < HZ_MINIMUM)) + hz = HZ_MINIMUM; + else if (__predict_false(hz > HZ_MAXIMUM)) + hz = HZ_MAXIMUM; + tick = 1000000 / hz; tick_sbt = SBT_1S / hz; tick_bt = sbttobt(tick_sbt); diff --git a/sys/sys/time.h b/sys/sys/time.h index 41d84aab5640..5d7f3f07234e 100644 --- a/sys/sys/time.h +++ b/sys/sys/time.h @@ -583,6 +583,13 @@ void timevaladd(struct timeval *t1, const struct timeval *t2); void timevalsub(struct timeval *t1, const struct timeval *t2); int tvtohz(struct timeval *tv); +/* + * The following HZ limits allow the tvtohz() function + * to only use integer computations. + */ +#define HZ_MAXIMUM (INT_MAX / (1000000 >> 6)) /* 137kHz */ +#define HZ_MINIMUM 8 /* hz */ + #define TC_DEFAULTPERC 5 #define BT2FREQ(bt) \