* Re: sched: about vruntime overflow
[not found] <47CEA9C0E570484FBF22EF0D7EBCE5B534B17A98@szxema505-mbs.china.huawei.com>
@ 2015-07-07 9:10 ` Peter Zijlstra
2015-07-07 9:18 ` Gaohaifeng (A)
0 siblings, 1 reply; 2+ messages in thread
From: Peter Zijlstra @ 2015-07-07 9:10 UTC (permalink / raw)
To: Gaohaifeng (A); +Cc: linux-kernel, stephan.baerwolf, Huangjian (J)
On Tue, Jul 07, 2015 at 08:05:50AM +0000, Gaohaifeng (A) wrote:
> int main()
> {
> unsigned char a,b;
> a=251;
> b=254;
> b +=5; // b will overflow
> printf("a=%u \n",a);
> printf("b=%u \n",b);
> printf("(a-b<0)=%d\n",(a-b)<0);
If you look at entity_before() you'll notice that the correct statement
would be:
printf("(a-b<0)=%d\n",(signed char)(a-b)<0);
> printf("(a-b<0)=%d\n",((unsigned char)(a-250)-(unsigned char)(b-250)<0));
> return 0;
> }
^ permalink raw reply [flat|nested] 2+ messages in thread
* RE: sched: about vruntime overflow
2015-07-07 9:10 ` sched: about vruntime overflow Peter Zijlstra
@ 2015-07-07 9:18 ` Gaohaifeng (A)
0 siblings, 0 replies; 2+ messages in thread
From: Gaohaifeng (A) @ 2015-07-07 9:18 UTC (permalink / raw)
To: Peter Zijlstra; +Cc: linux-kernel, stephan.baerwolf, Huangjian (J)
Much Thanks!
On Tue, Jul 07, 2015 at 08:05:50AM +0000, Gaohaifeng (A) wrote:
> int main()
> {
> unsigned char a,b;
> a=251;
> b=254;
> b +=5; // b will overflow
> printf("a=%u \n",a);
> printf("b=%u \n",b);
> printf("(a-b<0)=%d\n",(a-b)<0);
If you look at entity_before() you'll notice that the correct statement would be:
printf("(a-b<0)=%d\n",(signed char)(a-b)<0);
> printf("(a-b<0)=%d\n",((unsigned char)(a-250)-(unsigned char)(b-250)<0));
> return 0;
> }
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2015-07-07 9:19 UTC | newest]
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[not found] <47CEA9C0E570484FBF22EF0D7EBCE5B534B17A98@szxema505-mbs.china.huawei.com>
2015-07-07 9:10 ` sched: about vruntime overflow Peter Zijlstra
2015-07-07 9:18 ` Gaohaifeng (A)
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