Messages in this thread |  | | Date | Wed, 31 Oct 2001 16:11:53 -0500 (EST) | From | "Richard B. Johnson" <> | Subject | Re: [Patch] Re: Nasty suprise with uptime |
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On Wed, 31 Oct 2001, Tim Schmielau wrote:
> On Wed, 31 Oct 2001, vda wrote: > [SNIPPED...] > > btw.: can someone please explain to me why do_timer uses > (*(unsigned long *)&jiffies)++; > instead of just doing jiffies++ ? > > Tim
It's an attempt to prevent the 'C' compiler from doing this:
movl (jiffies), %eax # Read incl %eax # Modify movl %eax, (jiffies) # Write
Instead, we want it to do this:
movl jiffies, %ebx # init a pointer incl (%ebx) # Modify directly
With some gcc versions, it works. Others, it doesn't hurt.
Cheers, Dick Johnson
Penguin : Linux version 2.4.1 on an i686 machine (799.53 BogoMips).
I was going to compile a list of innovations that could be attributed to Microsoft. Once I realized that Ctrl-Alt-Del was handled in the BIOS, I found that there aren't any.
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