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OS-6364 lx: USER_HZ of 1000 breaks broken code which assumes 100 HZ
Reviewed by: Patrick Mooney <patrick.mooney@joyent.com> Approved by: Patrick Mooney <patrick.mooney@joyent.com>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,62 @@ | ||
| /* | ||
| * This file and its contents are supplied under the terms of the | ||
| * Common Development and Distribution License ("CDDL"), version 1.0. | ||
| * You may only use this file in accordance with the terms of version | ||
| * 1.0 of the CDDL. | ||
| * | ||
| * A full copy of the text of the CDDL should have accompanied this | ||
| * source. A copy of the CDDL is also available via the Internet at | ||
| * http://www.illumos.org/license/CDDL. | ||
| */ | ||
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|
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| /* | ||
| * Copyright 2017 Joyent, Inc. | ||
| */ | ||
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| #ifndef _LX_USERHZ_H | ||
| #define _LX_USERHZ_H | ||
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| #ifdef __cplusplus | ||
| extern "C" { | ||
| #endif | ||
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| /* | ||
| * Within the kernel, Linux implements an internal hz that they refer to as a | ||
| * "jiffy". Linux can be built with different hz, but on modern kernels | ||
| * it is frequently 250. However, Linux has a separate concept for the hz | ||
| * that is visible outside the kernel. This is called "USER_HZ" and is the | ||
| * value returned by 'sysconf(_SC_CLK_TCK)'. This is almost universally set to | ||
| * 100hz. Some (lazy) applications just hardcode 100hz instead of checking. | ||
| * To accommodate these broken applications, we always work with a USER_HZ of | ||
| * 100 and scale accordingly. See the Linux time(7) man page for a more | ||
| * detailed discussion of their behavior. See the comment in our | ||
| * uts/common/conf/param.c for a discussion of valid native hz values. | ||
| * | ||
| * There are a few interfaces which expose a clock_t to user-land and which | ||
| * need to be considered for USER_HZ adjustment. | ||
| * 1) The times(2) syscall. This is handled correctly. | ||
| * 2) The waitid(2) syscall passes a siginfo_t which contains si_stime and | ||
| * si_utime. Testing waitid(2) on various Linux distributions shows that the | ||
| * these fields are garbage. This aligns with the Linux waitid(2) man page, | ||
| * which describes the subset of the siginfo_t structure that is populated. | ||
| * Neither si_stime or si_utime are listed. | ||
| * 3) A sigaction(2) handler can pass a siginfo_t. This is only documented to | ||
| * occur when the sa_flags is SA_SIGINFO. The si_stime and si_utime are | ||
| * documented to only be populated when the signal is SIGCHLD. However, | ||
| * testing on Linux seems to show that these fields are not consistent | ||
| * with the corresponding times(2) data for the process, even for the | ||
| * SIGCHLD sigaction handler case. | ||
| * | ||
| * Although the siginfo_t si_stime and si_utime data for cases #2 and #3 is not | ||
| * consistent on Linux, we populate these fields correctly to be on the safe | ||
| * side. | ||
| */ | ||
| extern uint_t lx_hz_scale; | ||
| #define LX_USERHZ 100 | ||
| #define HZ_TO_LX_USERHZ(x) ((x) / lx_hz_scale) | ||
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| #ifdef __cplusplus | ||
| } | ||
| #endif | ||
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| #endif /* _LX_USERHZ_H */ |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,72 @@ | ||
| /* | ||
| * This file and its contents are supplied under the terms of the | ||
| * Common Development and Distribution License ("CDDL"), version 1.0. | ||
| * You may only use this file in accordance with the terms of version | ||
| * 1.0 of the CDDL. | ||
| * | ||
| * A full copy of the text of the CDDL should have accompanied this | ||
| * source. A copy of the CDDL is also available via the Internet at | ||
| * http://www.illumos.org/license/CDDL. | ||
| */ | ||
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| /* | ||
| * Copyright 2017, Joyent, Inc. | ||
| */ | ||
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| #include <sys/types.h> | ||
| #include <sys/systm.h> | ||
| #include <sys/thread.h> | ||
| #include <sys/proc.h> | ||
| #include <sys/times.h> | ||
| #include <sys/msacct.h> | ||
| #include <sys/lx_userhz.h> | ||
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| /* See the comment on LX_USERHZ for more details. */ | ||
| #define LX_NSEC_PER_USERHZ (NANOSEC / LX_USERHZ) | ||
| #define NSEC_TO_LX_USERHZ(nsec) ((nsec) / LX_NSEC_PER_USERHZ) | ||
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| /* | ||
| * Our times(2) implementation is based on the native times(2), but with | ||
| * the necessary scaling to adjust to USER_HZ. Also, Linux avoids writing | ||
| * to a NULL tp, whereas our native code returns EFAULT. | ||
| */ | ||
| long | ||
| lx_times(struct tms *tp) | ||
| { | ||
| proc_t *p = curproc; | ||
| struct tms p_time; | ||
| clock_t ret_lbolt; | ||
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| mutex_enter(&p->p_lock); | ||
| p_time.tms_utime = | ||
| (clock_t)NSEC_TO_LX_USERHZ(mstate_aggr_state(p, LMS_USER)); | ||
| p_time.tms_stime = | ||
| (clock_t)NSEC_TO_LX_USERHZ(mstate_aggr_state(p, LMS_SYSTEM)); | ||
| p_time.tms_cutime = HZ_TO_LX_USERHZ(p->p_cutime); | ||
| p_time.tms_cstime = HZ_TO_LX_USERHZ(p->p_cstime); | ||
| mutex_exit(&p->p_lock); | ||
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| #ifdef _SYSCALL32_IMPL | ||
| if (get_udatamodel() != DATAMODEL_NATIVE) { | ||
| struct tms32 t32; | ||
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| t32.tms_utime = p_time.tms_utime; | ||
| t32.tms_stime = p_time.tms_stime; | ||
| t32.tms_cutime = p_time.tms_cutime; | ||
| t32.tms_cstime = p_time.tms_cstime; | ||
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| if (tp != NULL && copyout(&t32, tp, sizeof (t32)) != 0) | ||
| return (set_errno(EFAULT)); | ||
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| ret_lbolt = ddi_get_lbolt(); | ||
| return ((clock32_t)HZ_TO_LX_USERHZ(ret_lbolt)); | ||
| } else | ||
| #endif /* _SYSCALL32_IMPL */ | ||
| { | ||
| if (tp != NULL && copyout(&p_time, tp, sizeof (p_time)) != 0) | ||
| return (set_errno(EFAULT)); | ||
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| ret_lbolt = ddi_get_lbolt(); | ||
| return (HZ_TO_LX_USERHZ(ret_lbolt)); | ||
| } | ||
| } |
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