Messages in this thread |  | | | Subject | Re: [PATCH #2] console lock grabbed too early in printk... | | Date | Mon, 3 Jul 2000 23:27:36 +0100 (BST) | | From | Alan Cox <> |
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> is not held (which is the only case that matters, because otherwise, > access would block on the console_lock currently), we have the following > (for the x86 at least, the others are similar): > > spin_lock: > "xchgb %b0,%1" > "cmp $1, ..." > "jz ..." > > Note that the jump is not taken, so it is one cycle.
The xchgb is a locked bus access so takes an awful lot longer, especially on earlier cpus
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