Message ID | 1497286107-974183-5-git-send-email-pasha.tatashin@oracle.com |
---|---|
State | Changes Requested |
Delegated to: | David Miller |
Headers | show |
From: Pavel Tatashin <pasha.tatashin@oracle.com> Date: Mon, 12 Jun 2017 12:48:23 -0400 > @@ -164,7 +164,7 @@ static unsigned long tick_add_tick(unsigned long adj) > return new_tick; > } > > -static struct sparc64_tick_ops tick_operations __read_mostly = { > +static struct sparc64_tick_ops tick_operations __aligned(64) __read_mostly = { Please use __cacheline_aligned instead of "__aligned(64)" -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Dave, Thank you for your comments: When I use __cacheline_aligned instead of __aligned(64) I am getting the following error: error: section of 'tick_operations' conflicts with previous declaration The __section__ difference causes the issue: __cacheline_aligned= __attribute__((__aligned__((1 << 6)), __section__(".data..cacheline_aligned"))) vs __aligned(64) = __attribute__((aligned(64))) Pasha On 2017-06-12 15:06, David Miller wrote: > From: Pavel Tatashin <pasha.tatashin@oracle.com> > Date: Mon, 12 Jun 2017 12:48:23 -0400 > >> @@ -164,7 +164,7 @@ static unsigned long tick_add_tick(unsigned long adj) >> return new_tick; >> } >> >> -static struct sparc64_tick_ops tick_operations __read_mostly = { >> +static struct sparc64_tick_ops tick_operations __aligned(64) __read_mostly = { > > Please use __cacheline_aligned instead of "__aligned(64)" > -- > To unsubscribe from this list: send the line "unsubscribe sparclinux" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: Pasha Tatashin <pasha.tatashin@oracle.com> Date: Mon, 12 Jun 2017 15:55:44 -0400 > Thank you for your comments: > > When I use __cacheline_aligned instead of __aligned(64) I am getting > the following error: > > error: section of 'tick_operations' conflicts with previous > declaration > > The __section__ difference causes the issue: > > __cacheline_aligned= __attribute__((__aligned__((1 << 6)), > __section__(".data..cacheline_aligned"))) > > vs > > __aligned(64) = __attribute__((aligned(64))) Perhaps get rid of the __read_mostly. -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
> Perhaps get rid of the __read_mostly.
OK, or as alternative we could do something like:
__read_mostly __aligned(SMP_CACHE_BYTES)
Not sure what is better though.
Pasha
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From: Pasha Tatashin <pasha.tatashin@oracle.com> Date: Mon, 12 Jun 2017 16:02:54 -0400 >> Perhaps get rid of the __read_mostly. > > OK, or as alternative we could do something like: > > __read_mostly __aligned(SMP_CACHE_BYTES) > > Not sure what is better though. Better not to put alignment induced gaps into the __read_only section like this I think. -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/sparc/include/asm/timer_64.h b/arch/sparc/include/asm/timer_64.h index fce4150..bde2cc4 100644 --- a/arch/sparc/include/asm/timer_64.h +++ b/arch/sparc/include/asm/timer_64.h @@ -9,7 +9,12 @@ #include <linux/types.h> #include <linux/init.h> +/* The most frequently accessed fields should be first, + * to fit into the same cacheline. + */ struct sparc64_tick_ops { + unsigned long ticks_per_nsec_quotient; + unsigned long offset; unsigned long long (*get_tick)(void); int (*add_compare)(unsigned long); unsigned long softint_mask; diff --git a/arch/sparc/kernel/time_64.c b/arch/sparc/kernel/time_64.c index 5f53b74..d654f5c 100644 --- a/arch/sparc/kernel/time_64.c +++ b/arch/sparc/kernel/time_64.c @@ -164,7 +164,7 @@ static unsigned long tick_add_tick(unsigned long adj) return new_tick; } -static struct sparc64_tick_ops tick_operations __read_mostly = { +static struct sparc64_tick_ops tick_operations __aligned(64) __read_mostly = { .name = "tick", .init_tick = tick_init_tick, .disable_irq = tick_disable_irq, @@ -391,9 +391,6 @@ static int hbtick_add_compare(unsigned long adj) .softint_mask = 1UL << 0, }; -static unsigned long timer_ticks_per_nsec_quotient __read_mostly; -static unsigned long timer_offset __read_mostly; - unsigned long cmos_regs; EXPORT_SYMBOL(cmos_regs); @@ -784,11 +781,11 @@ void __init time_init(void) tb_ticks_per_usec = freq / USEC_PER_SEC; - timer_ticks_per_nsec_quotient = + tick_operations.ticks_per_nsec_quotient = clocksource_hz2mult(freq, SPARC64_NSEC_PER_CYC_SHIFT); - timer_offset = (tick_operations.get_tick() - * timer_ticks_per_nsec_quotient) + tick_operations.offset = (tick_operations.get_tick() + * tick_operations.ticks_per_nsec_quotient) >> SPARC64_NSEC_PER_CYC_SHIFT; clocksource_tick.name = tick_operations.name; @@ -816,11 +813,11 @@ void __init time_init(void) unsigned long long sched_clock(void) { + unsigned long quotient = tick_operations.ticks_per_nsec_quotient; + unsigned long offset = tick_operations.offset; unsigned long ticks = tick_operations.get_tick(); - return ((ticks * timer_ticks_per_nsec_quotient) - >> SPARC64_NSEC_PER_CYC_SHIFT) - - timer_offset; + return ((ticks * quotient) >> SPARC64_NSEC_PER_CYC_SHIFT) - offset; } int read_current_timer(unsigned long *timer_val)