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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This archive was generated by hypermail 2b29 : Wed Oct 31 2001 - 21:00:46 EST