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qemu-patch-raspberry4
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cpu-exec: update icount after each TB_EXIT 

There is no particular reason we shouldn't update the global system
icount time as we exit each TranslationBlock run. This ensures the
main-loop doesn't have to wait until we exit to the outer loop for
executed instructions to be credited to timer_state.

The prepare_icount_for_run function is slightly tweaked to match the
logic we run in cpu_loop_exec_tb.

Based on Paolo's original suggestion.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
stable-2.9
Alex Bennée 2017-04-05 12:35:48 +01:00
parent 512d3c8071
commit eda5f7c6a1
2 changed files with 12 additions and 20 deletions
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14
cpu-exec.c
View File

@ -600,13 +600,13 @@ static inline void cpu_loop_exec_tb(CPUState *cpu, TranslationBlock *tb,
/* Instruction counter expired. */
assert(use_icount);
#ifndef CONFIG_USER_ONLY
if (cpu->icount_extra) {
/* Refill decrementer and continue execution. */
cpu->icount_extra += insns_left;
insns_left = MIN(0xffff, cpu->icount_extra);
cpu->icount_extra -= insns_left;
cpu->icount_decr.u16.low = insns_left;
} else {
/* Ensure global icount has gone forward */
cpu_update_icount(cpu);
/* Refill decrementer and continue execution. */
insns_left = MIN(0xffff, cpu->icount_budget);
cpu->icount_decr.u16.low = insns_left;
cpu->icount_extra = cpu->icount_budget - insns_left;
if (!cpu->icount_extra) {
/* Execute any remaining instructions, then let the main loop
* handle the next event.
*/

18
cpus.c
View File

@ -1211,8 +1211,7 @@ static void handle_icount_deadline(void)
static void prepare_icount_for_run(CPUState *cpu)
{
if (use_icount) {
int64_t count;
int decr;
int insns_left;
/* These should always be cleared by process_icount_data after
* each vCPU execution. However u16.high can be raised
@ -1221,17 +1220,10 @@ static void prepare_icount_for_run(CPUState *cpu)
g_assert(cpu->icount_decr.u16.low == 0);
g_assert(cpu->icount_extra == 0);
count = tcg_get_icount_limit();
/* To calculate what we have executed so far we need to know
* what we originally budgeted to run this cycle */
cpu->icount_budget = count;
decr = (count > 0xffff) ? 0xffff : count;
count -= decr;
cpu->icount_decr.u16.low = decr;
cpu->icount_extra = count;
cpu->icount_budget = tcg_get_icount_limit();
insns_left = MIN(0xffff, cpu->icount_budget);
cpu->icount_decr.u16.low = insns_left;
cpu->icount_extra = cpu->icount_budget - insns_left;
}
}