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lguest: tidy up documentation 

After Adrian Bunk's "make async_hcall static" moved things around, update
comments to match (aka "make Guest").

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2007-11-05 21:55:57 +11:00
parent fad23fc78b
commit 633872b980
1 changed files with 21 additions and 22 deletions
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43
arch/x86/lguest/boot.c
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@ -93,27 +93,7 @@ struct lguest_data lguest_data = {
};
static cycle_t clock_base;
/*G:035 Notice the lazy_hcall() above, rather than hcall(). This is our first
* real optimization trick!
*
* When lazy_mode is set, it means we're allowed to defer all hypercalls and do
* them as a batch when lazy_mode is eventually turned off. Because hypercalls
* are reasonably expensive, batching them up makes sense. For example, a
* large munmap might update dozens of page table entries: that code calls
* paravirt_enter_lazy_mmu(), does the dozen updates, then calls
* lguest_leave_lazy_mode().
*
* So, when we're in lazy mode, we call async_hypercall() to store the call for
* future processing. When lazy mode is turned off we issue a hypercall to
* flush the stored calls.
*/
static void lguest_leave_lazy_mode(void)
{
paravirt_leave_lazy(paravirt_get_lazy_mode());
hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0);
}
/* async_hcall() is pretty simple: I'm quite proud of it really. We have a
/*G:037 async_hcall() is pretty simple: I'm quite proud of it really. We have a
* ring buffer of stored hypercalls which the Host will run though next time we
* do a normal hypercall. Each entry in the ring has 4 slots for the hypercall
* arguments, and a "hcall_status" word which is 0 if the call is ready to go,
@ -151,6 +131,18 @@ static void async_hcall(unsigned long call, unsigned long arg1,
local_irq_restore(flags);
}
/*G:035 Notice the lazy_hcall() above, rather than hcall(). This is our first
* real optimization trick!
*
* When lazy_mode is set, it means we're allowed to defer all hypercalls and do
* them as a batch when lazy_mode is eventually turned off. Because hypercalls
* are reasonably expensive, batching them up makes sense. For example, a
* large munmap might update dozens of page table entries: that code calls
* paravirt_enter_lazy_mmu(), does the dozen updates, then calls
* lguest_leave_lazy_mode().
*
* So, when we're in lazy mode, we call async_hcall() to store the call for
* future processing. */
static void lazy_hcall(unsigned long call,
unsigned long arg1,
unsigned long arg2,
@ -161,7 +153,14 @@ static void lazy_hcall(unsigned long call,
else
async_hcall(call, arg1, arg2, arg3);
}
/*:*/
/* When lazy mode is turned off reset the per-cpu lazy mode variable and then
* issue a hypercall to flush any stored calls. */
static void lguest_leave_lazy_mode(void)
{
paravirt_leave_lazy(paravirt_get_lazy_mode());
hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0);
}
/*G:033
* After that diversion we return to our first native-instruction