[parisc-linux] ldcw in __pthread_acquire

[Matthew Wilcox]

On Mon, Dec 18, 2000 at 07:49:32AM -0700, LaMont Jones wrote:
> > Since hppa its apparently 2 clocks to the syscall the numbers are apparently
> > different.
> 
> Actually, the sequence consists of:
> 
> libc_stub:
> 	bl	gateway_page_addr
> 	...
> 
> gateway_page_addr:
> 	gate	.+8
> 	...
> 	...
> 
> And we find ourselves in kernel mode after 2 branches (unconditional
> and pre-computed ==> predict correctly) and two delay slots.  At that
> point we have kernel data structures at our fingertips, but have in no
> way done a complete 'syscall' entry - those are (at least on hp-ux) a
> bit more expensive...  (It also means that kernel vs user detection in
> traps code needs to look at the priv level, not the stack pointer...)

... ignoring the potential pain of TLB misses caused by losing locality.
But this is merely a quibble, I think.

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