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From: Jindrich Makovicka <makovick-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: "Jindrich Makovicka" <makovick-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
Subject: Re: kvm-37 problem w/ 64-bit division in lapic.c
Date: Mon, 10 Sep 2007 18:26:28 +0200	[thread overview]
Message-ID: <20070910182628.5fc7090f@holly> (raw)
In-Reply-To: <5f0e26840709100249y239692c2gcdd3938fc6b23b6c-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

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On Mon, 10 Sep 2007 11:49:02 +0200
"Jindrich Makovicka" <makovick-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:

> On 9/10/07, Dong, Eddie <eddie.dong-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> wrote:
> > div64_32 is enough, does this function exist?
> 
> afaik, __div64_32 is architecture specific, but do_div() could be
> actually used here.

This version should be faster.

Signed-off-by: Jindrich Makovicka <makovick-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

-- 
Jindrich Makovicka

[-- Attachment #2: lapic.c.diff2 --]
[-- Type: application/octet-stream, Size: 673 bytes --]

--- lapic.c~	2007-09-09 16:12:38.000000000 +0200
+++ lapic.c	2007-09-10 18:16:34.000000000 +0200
@@ -494,7 +494,7 @@
 
 static u32 apic_get_tmcct(struct kvm_lapic *apic)
 {
-	u32 counter_passed;
+	u64 counter_passed;
 	ktime_t passed, now = apic->timer.dev.base->get_time();
 	u32 tmcct = apic_get_reg(apic, APIC_TMICT);
 
@@ -512,8 +512,8 @@
 	} else
 		passed = ktime_sub(now, apic->timer.last_update);
 
-	counter_passed = div64_64(ktime_to_ns(passed),
-				  (APIC_BUS_CYCLE_NS * apic->timer.divide_count));
+	counter_passed = ktime_to_ns(passed);
+	do_div(counter_passed, APIC_BUS_CYCLE_NS * apic->timer.divide_count);
 	tmcct -= counter_passed;
 
 	if (tmcct <= 0) {

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  parent reply	other threads:[~2007-09-10 16:26 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-09-09 11:05 [ANNOUNCE] kvm-37 release Avi Kivity
2007-09-09 14:26 ` Jindrich Makovicka
     [not found] ` <46E3D369.8000401-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-09-09 15:36   ` kvm-37 problem w/ 64-bit division in lapic.c Jindrich Makovicka
2007-09-09 15:45     ` Avi Kivity
2007-09-10  9:20     ` Dong, Eddie
     [not found]       ` <10EA09EFD8728347A513008B6B0DA77A02108583-wq7ZOvIWXbNpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2007-09-10  9:49         ` Jindrich Makovicka
     [not found]           ` <5f0e26840709100249y239692c2gcdd3938fc6b23b6c-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2007-09-10 16:26             ` Jindrich Makovicka [this message]
2007-09-12  8:05               ` Avi Kivity
     [not found]                 ` <46E79DCA.70101-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-09-12  9:43                   ` Dong, Eddie
     [not found]                     ` <10EA09EFD8728347A513008B6B0DA77A0210915A-wq7ZOvIWXbNpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2007-09-12  9:56                       ` Avi Kivity

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