Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge tag 'timers-urgent-2025-09-07' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer fix from Ingo Molnar:
"Fix a severe slowdown regression in the timer vDSO code related to the
while() loop in __iter_div_u64_rem(), when the AUX-clock is enabled"
* tag 'timers-urgent-2025-09-07' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
vdso/vsyscall: Avoid slow division loop in auxiliary clock update
+18
-5
+8
-1
include/linux/timekeeper_internal.h
+8
-1
include/linux/timekeeper_internal.h
···
76
76
* @cs_was_changed_seq: The sequence number of clocksource change events
77
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* @clock_valid: Indicator for valid clock
78
78
* @monotonic_to_boot: CLOCK_MONOTONIC to CLOCK_BOOTTIME offset
79
+
* @monotonic_to_aux: CLOCK_MONOTONIC to CLOCK_AUX offset
79
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* @cycle_interval: Number of clock cycles in one NTP interval
80
81
* @xtime_interval: Number of clock shifted nano seconds in one NTP
81
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* interval.
···
117
116
*
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* @offs_aux is used by the auxiliary timekeepers which do not utilize any
119
118
* of the regular timekeeper offset fields.
119
+
*
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+
* @monotonic_to_aux is a timespec64 representation of @offs_aux to
121
+
* accelerate the VDSO update for CLOCK_AUX.
120
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*
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* The cacheline ordering of the structure is optimized for in kernel usage of
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* the ktime_get() and ktime_get_ts64() family of time accessors. Struct
···
163
159
u8 cs_was_changed_seq;
164
160
u8 clock_valid;
165
161
166
-
struct timespec64 monotonic_to_boot;
162
+
union {
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+
struct timespec64 monotonic_to_boot;
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+
struct timespec64 monotonic_to_aux;
165
+
};
167
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u64 cycle_interval;
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168
u64 xtime_interval;
+8
-2
kernel/time/timekeeping.c
+8
-2
kernel/time/timekeeping.c
···
83
83
}
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84
#endif
85
85
86
+
static inline void tk_update_aux_offs(struct timekeeper *tk, ktime_t offs)
87
+
{
88
+
tk->offs_aux = offs;
89
+
tk->monotonic_to_aux = ktime_to_timespec64(offs);
90
+
}
91
+
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/* flag for if timekeeping is suspended */
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int __read_mostly timekeeping_suspended;
88
94
···
1512
1506
timekeeping_restore_shadow(tkd);
1513
1507
return -EINVAL;
1514
1508
}
1515
-
tks->offs_aux = offs;
1509
+
tk_update_aux_offs(tks, offs);
1516
1510
}
1517
1511
1518
1512
timekeeping_update_from_shadow(tkd, TK_UPDATE_ALL);
···
2943
2937
* xtime ("realtime") is not applicable for auxiliary clocks and
2944
2938
* kept in sync with "monotonic".
2945
2939
*/
2946
-
aux_tks->offs_aux = ktime_sub(timespec64_to_ktime(*tnew), tnow);
2940
+
tk_update_aux_offs(aux_tks, ktime_sub(timespec64_to_ktime(*tnew), tnow));
2947
2941
2948
2942
timekeeping_update_from_shadow(aux_tkd, TK_UPDATE_ALL);
2949
2943
return 0;
+2
-2
kernel/time/vsyscall.c
+2
-2
kernel/time/vsyscall.c
···
159
159
if (clock_mode != VDSO_CLOCKMODE_NONE) {
160
160
fill_clock_configuration(vc, &tk->tkr_mono);
161
161
162
-
vdso_ts->sec = tk->xtime_sec;
162
+
vdso_ts->sec = tk->xtime_sec + tk->monotonic_to_aux.tv_sec;
163
163
164
164
nsec = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
165
-
nsec += tk->offs_aux;
165
+
nsec += tk->monotonic_to_aux.tv_nsec;
166
166
vdso_ts->sec += __iter_div_u64_rem(nsec, NSEC_PER_SEC, &nsec);
167
167
nsec = nsec << tk->tkr_mono.shift;
168
168
vdso_ts->nsec = nsec;