Re: [PATCH v4.16-rc5 1/2] x86/vdso: VDSO should handle clock_gettime(CLOCK_MONOTONIC_RAW) without syscall
Hi, Thank you for the patch! Yet something to improve: [auto build test ERROR on v4.16-rc4] [also build test ERROR on next-20180319] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] url: https://github.com/0day-ci/linux/commits/jason-vas-dias-gmail-com/x86-vdso-VDSO-should-handle-clock_gettime-CLOCK_MONOTONIC_RAW-without-syscall/20180319-021527 config: x86_64-randconfig-in0-03200329 (attached as .config) compiler: gcc-7 (Debian 7.3.0-1) 7.3.0 reproduce: # save the attached .config to linux build tree make ARCH=x86_64 Note: the linux-review/jason-vas-dias-gmail-com/x86-vdso-VDSO-should-handle-clock_gettime-CLOCK_MONOTONIC_RAW-without-syscall/20180319-021527 HEAD e19190a6cf1c0e065fe6e3b1b3073e1586d0b6a9 builds fine. It only hurts bisectibility. All errors (new ones prefixed by >>): >> arch/x86/entry/vdso/vdso32.so.dbg: undefined symbols found --- 0-DAY kernel test infrastructureOpen Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation .config.gz Description: application/gzip
Re: [PATCH v4.16-rc5 1/2] x86/vdso: VDSO should handle clock_gettime(CLOCK_MONOTONIC_RAW) without syscall
Hi,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on v4.16-rc4]
[also build test ERROR on next-20180316]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system]
url:
https://github.com/0day-ci/linux/commits/jason-vas-dias-gmail-com/x86-vdso-VDSO-should-handle-clock_gettime-CLOCK_MONOTONIC_RAW-without-syscall/20180319-021527
config: x86_64-randconfig-v0-03200333 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
# save the attached .config to linux build tree
make ARCH=x86_64
Note: the
linux-review/jason-vas-dias-gmail-com/x86-vdso-VDSO-should-handle-clock_gettime-CLOCK_MONOTONIC_RAW-without-syscall/20180319-021527
HEAD e19190a6cf1c0e065fe6e3b1b3073e1586d0b6a9 builds fine.
It only hurts bisectibility.
All errors (new ones prefixed by >>):
arch/x86/entry/vdso/vclock_gettime.o: In function `__vdso_clock_gettime':
>> arch/x86/entry/vdso/vclock_gettime.c:314: undefined reference to
>> `__x86_indirect_thunk_rax'
/usr/bin/ld: arch/x86/entry/vdso/vclock_gettime.o: relocation R_X86_64_PC32
against undefined symbol `__x86_indirect_thunk_rax' can not be used when making
a shared object; recompile with -fPIC
/usr/bin/ld: final link failed: Bad value
>> collect2: error: ld returned 1 exit status
--
>> objcopy: 'arch/x86/entry/vdso/vdso64.so.dbg': No such file
--
arch/x86//entry/vdso/vclock_gettime.o: In function `__vdso_clock_gettime':
arch/x86//entry/vdso/vclock_gettime.c:314: undefined reference to
`__x86_indirect_thunk_rax'
/usr/bin/ld: arch/x86//entry/vdso/vclock_gettime.o: relocation R_X86_64_PC32
against undefined symbol `__x86_indirect_thunk_rax' can not be used when making
a shared object; recompile with -fPIC
/usr/bin/ld: final link failed: Bad value
>> collect2: error: ld returned 1 exit status
vim +314 arch/x86/entry/vdso/vclock_gettime.c
da15cfda arch/x86/vdso/vclock_gettime.c John Stultz
2009-08-19 311
23adec55 arch/x86/vdso/vclock_gettime.c Steven Rostedt
2008-05-12 312 notrace int __vdso_clock_gettime(clockid_t clock, struct
timespec *ts)
2aae950b arch/x86_64/vdso/vclock_gettime.cAndi Kleen
2007-07-21 313 {
2aae950b arch/x86_64/vdso/vclock_gettime.cAndi Kleen
2007-07-21 @314 switch (clock) {
2aae950b arch/x86_64/vdso/vclock_gettime.cAndi Kleen
2007-07-21 315 case CLOCK_REALTIME:
ce39c640 arch/x86/vdso/vclock_gettime.c Stefani Seibold
2014-03-17 316 if (do_realtime(ts) == VCLOCK_NONE)
ce39c640 arch/x86/vdso/vclock_gettime.c Stefani Seibold
2014-03-17 317 goto fallback;
da15cfda arch/x86/vdso/vclock_gettime.c John Stultz
2009-08-19 318 break;
2aae950b arch/x86_64/vdso/vclock_gettime.cAndi Kleen
2007-07-21 319 case CLOCK_MONOTONIC:
ce39c640 arch/x86/vdso/vclock_gettime.c Stefani Seibold
2014-03-17 320 if (do_monotonic(ts) == VCLOCK_NONE)
ce39c640 arch/x86/vdso/vclock_gettime.c Stefani Seibold
2014-03-17 321 goto fallback;
da15cfda arch/x86/vdso/vclock_gettime.c John Stultz
2009-08-19 322 break;
d3dd2426 arch/x86/entry/vdso/vclock_gettime.c jason.vas.d...@gmail.com
2018-03-17 323 case CLOCK_MONOTONIC_RAW:
d3dd2426 arch/x86/entry/vdso/vclock_gettime.c jason.vas.d...@gmail.com
2018-03-17 324 if (do_monotonic_raw(ts) == VCLOCK_NONE)
d3dd2426 arch/x86/entry/vdso/vclock_gettime.c jason.vas.d...@gmail.com
2018-03-17 325 goto fallback;
d3dd2426 arch/x86/entry/vdso/vclock_gettime.c jason.vas.d...@gmail.com
2018-03-17 326 break;
da15cfda arch/x86/vdso/vclock_gettime.c John Stultz
2009-08-19 327 case CLOCK_REALTIME_COARSE:
ce39c640 arch/x86/vdso/vclock_gettime.c Stefani Seibold
2014-03-17 328 do_realtime_coarse(ts);
ce39c640 arch/x86/vdso/vclock_gettime.c Stefani Seibold
2014-03-17 329 break;
da15cfda arch/x86/vdso/vclock_gettime.c John Stultz
2009-08-19 330 case CLOCK_MONOTONIC_COARSE:
ce39c640 arch/x86/vdso/vclock_gettime.c Stefani Seibold
2014-03-17 331 do_monotonic_coarse(ts);
ce39c640 arch/x86/vdso/vclock_gettime.c Stefani Seibold
2014-03-17 332 break;
ce39c640 arch/x86/vdso/vclock_gettime.c Stefani Seibold
2014-03-17 333 default:
ce39c640 arch/x86/vdso/vclock_gettime.c Stefani Seibold
2014-03-17 334 goto fallback;
2aae950b arch/x86_64/vdso/vclock_gettime.cAndi Kleen
2007-07-21 335 }
0d7b8547 arch/x86/vdso/vclock_gettime.c Andy
[PATCH v4.16-rc5 1/2] x86/vdso: VDSO should handle clock_gettime(CLOCK_MONOTONIC_RAW) without syscall
This patch makes the vDSO handle clock_gettime(CLOCK_MONOTONIC_RAW,&ts)
calls in the same way it handles clock_gettime(CLOCK_MONOTONIC,&ts)
calls,
reducing latency from @ 200-1000ns to @ 20ns.
diff --git a/arch/x86/entry/vdso/vclock_gettime.c
b/arch/x86/entry/vdso/vclock_gettime.c
index f19856d..843b0a6 100644
--- a/arch/x86/entry/vdso/vclock_gettime.c
+++ b/arch/x86/entry/vdso/vclock_gettime.c
@@ -182,27 +182,49 @@ notrace static u64 vread_tsc(void)
return last;
}
-notrace static inline u64 vgetsns(int *mode)
+notrace static inline __always_inline u64 vgetcycles(int *mode)
{
- u64 v;
- cycles_t cycles;
-
- if (gtod->vclock_mode == VCLOCK_TSC)
- cycles = vread_tsc();
+ switch (gtod->vclock_mode) {
+ case VCLOCK_TSC:
+ return vread_tsc();
#ifdef CONFIG_PARAVIRT_CLOCK
- else if (gtod->vclock_mode == VCLOCK_PVCLOCK)
- cycles = vread_pvclock(mode);
+ case VCLOCK_PVCLOCK:
+ return vread_pvclock(mode);
#endif
#ifdef CONFIG_HYPERV_TSCPAGE
- else if (gtod->vclock_mode == VCLOCK_HVCLOCK)
- cycles = vread_hvclock(mode);
+ case VCLOCK_HVCLOCK:
+ return vread_hvclock(mode);
#endif
- else
+ default:
+ break;
+ }
+ return 0;
+}
+
+notrace static inline u64 vgetsns(int *mode)
+{
+ u64 v;
+ cycles_t cycles = vgetcycles(mode);
+
+ if (cycles == 0)
return 0;
+
v = (cycles - gtod->cycle_last) & gtod->mask;
return v * gtod->mult;
}
+notrace static inline u64 vgetsns_raw(int *mode)
+{
+ u64 v;
+ cycles_t cycles = vgetcycles(mode);
+
+ if (cycles == 0)
+ return 0;
+
+ v = (cycles - gtod->cycle_last) & gtod->mask;
+ return v * gtod->raw_mult;
+}
+
/* Code size doesn't matter (vdso is 4k anyway) and this is faster. */
notrace static int __always_inline do_realtime(struct timespec *ts)
{
@@ -246,6 +268,27 @@ notrace static int __always_inline do_monotonic(struct
timespec *ts)
return mode;
}
+notrace static __always_inline int do_monotonic_raw(struct timespec *ts)
+{
+ unsigned long seq;
+ u64 ns;
+ int mode;
+
+ do {
+ seq = gtod_read_begin(gtod);
+ mode = gtod->vclock_mode;
+ ts->tv_sec = gtod->monotonic_time_raw_sec;
+ ns = gtod->monotonic_time_raw_nsec;
+ ns += vgetsns_raw(&mode);
+ ns >>= gtod->raw_shift;
+ } while (unlikely(gtod_read_retry(gtod, seq)));
+
+ ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
+ ts->tv_nsec = ns;
+
+ return mode;
+}
+
notrace static void do_realtime_coarse(struct timespec *ts)
{
unsigned long seq;
@@ -277,6 +320,10 @@ notrace int __vdso_clock_gettime(clockid_t clock, struct
timespec *ts)
if (do_monotonic(ts) == VCLOCK_NONE)
goto fallback;
break;
+ case CLOCK_MONOTONIC_RAW:
+ if (do_monotonic_raw(ts) == VCLOCK_NONE)
+ goto fallback;
+ break;
case CLOCK_REALTIME_COARSE:
do_realtime_coarse(ts);
break;
diff --git a/arch/x86/entry/vsyscall/vsyscall_gtod.c
b/arch/x86/entry/vsyscall/vsyscall_gtod.c
index e1216dd..c4d89b6 100644
--- a/arch/x86/entry/vsyscall/vsyscall_gtod.c
+++ b/arch/x86/entry/vsyscall/vsyscall_gtod.c
@@ -44,6 +44,8 @@ void update_vsyscall(struct timekeeper *tk)
vdata->mask = tk->tkr_mono.mask;
vdata->mult = tk->tkr_mono.mult;
vdata->shift= tk->tkr_mono.shift;
+ vdata->raw_mult = tk->tkr_raw.mult;
+ vdata->raw_shift= tk->tkr_raw.shift;
vdata->wall_time_sec= tk->xtime_sec;
vdata->wall_time_snsec = tk->tkr_mono.xtime_nsec;
@@ -74,5 +76,8 @@ void update_vsyscall(struct timekeeper *tk)
vdata->monotonic_time_coarse_sec++;
}
+ vdata->monotonic_time_raw_sec = tk->raw_sec;
+ vdata->monotonic_time_raw_nsec = tk->tkr_raw.xtime_nsec;
+
gtod_write_end(vdata);
}
diff --git a/arch/x86/include/asm/vgtod.h b/arch/x86/include/asm/vgtod.h
index fb856c9..ec1a37c 100644
--- a/arch/x86/include/asm/vgtod.h
+++ b/arch/x86/include/asm/vgtod.h
@@ -22,7 +22,8 @@ struct vsyscall_gtod_data {
u64 mask;
u32 mult;
u32 shift;
-
+ u32 raw_mult;
+ u32 raw_shift;
/* open coded 'struct timespec' */
u64 wall_time_snsec;
gtod_long_t wall_time_sec;
@@ -32,6 +33,8 @@ struct vsyscall_gtod_data {
gtod_long_t wall_time_coarse_nsec;
gtod_long_t monotonic_time_coarse_sec;
gtod_long_t monotonic_time_coarse_nsec;
+ gtod_long_t monotonic_time_raw_sec;
+ gtod_long_t monotonic_time_raw_ns
