diff options
author | Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> | 2008-06-12 04:47:56 -0400 |
---|---|---|
committer | Ingo Molnar <mingo@elte.hu> | 2008-06-12 04:47:56 -0400 |
commit | f595ec964daf7f99668039d7303ddedd09a75142 (patch) | |
tree | 4ee6679105f0437995ff200f10885598921ae1cd /arch/x86 | |
parent | 5e70b7f3c24468bb1635b295945edb48ecd9656a (diff) |
common implementation of iterative div/mod
We have a few instances of the open-coded iterative div/mod loop, used
when we don't expcet the dividend to be much bigger than the divisor.
Unfortunately modern gcc's have the tendency to strength "reduce" this
into a full mod operation, which isn't necessarily any faster, and
even if it were, doesn't exist if gcc implements it in libgcc.
The workaround is to put a dummy asm statement in the loop to prevent
gcc from performing the transformation.
This patch creates a single implementation of this loop, and uses it
to replace the open-coded versions I know about.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Segher Boessenkool <segher@kernel.crashing.org>
Cc: Christian Kujau <lists@nerdbynature.de>
Cc: Robert Hancock <hancockr@shaw.ca>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86')
-rw-r--r-- | arch/x86/xen/time.c | 13 |
1 files changed, 3 insertions, 10 deletions
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c index c39e1a5aa241..52b2e3856980 100644 --- a/arch/x86/xen/time.c +++ b/arch/x86/xen/time.c | |||
@@ -12,6 +12,7 @@ | |||
12 | #include <linux/clocksource.h> | 12 | #include <linux/clocksource.h> |
13 | #include <linux/clockchips.h> | 13 | #include <linux/clockchips.h> |
14 | #include <linux/kernel_stat.h> | 14 | #include <linux/kernel_stat.h> |
15 | #include <linux/math64.h> | ||
15 | 16 | ||
16 | #include <asm/xen/hypervisor.h> | 17 | #include <asm/xen/hypervisor.h> |
17 | #include <asm/xen/hypercall.h> | 18 | #include <asm/xen/hypercall.h> |
@@ -150,11 +151,7 @@ static void do_stolen_accounting(void) | |||
150 | if (stolen < 0) | 151 | if (stolen < 0) |
151 | stolen = 0; | 152 | stolen = 0; |
152 | 153 | ||
153 | ticks = 0; | 154 | ticks = iter_div_u64_rem(stolen, NS_PER_TICK, &stolen); |
154 | while (stolen >= NS_PER_TICK) { | ||
155 | ticks++; | ||
156 | stolen -= NS_PER_TICK; | ||
157 | } | ||
158 | __get_cpu_var(residual_stolen) = stolen; | 155 | __get_cpu_var(residual_stolen) = stolen; |
159 | account_steal_time(NULL, ticks); | 156 | account_steal_time(NULL, ticks); |
160 | 157 | ||
@@ -166,11 +163,7 @@ static void do_stolen_accounting(void) | |||
166 | if (blocked < 0) | 163 | if (blocked < 0) |
167 | blocked = 0; | 164 | blocked = 0; |
168 | 165 | ||
169 | ticks = 0; | 166 | ticks = iter_div_u64_rem(blocked, NS_PER_TICK, &blocked); |
170 | while (blocked >= NS_PER_TICK) { | ||
171 | ticks++; | ||
172 | blocked -= NS_PER_TICK; | ||
173 | } | ||
174 | __get_cpu_var(residual_blocked) = blocked; | 167 | __get_cpu_var(residual_blocked) = blocked; |
175 | account_steal_time(idle_task(smp_processor_id()), ticks); | 168 | account_steal_time(idle_task(smp_processor_id()), ticks); |
176 | } | 169 | } |