[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [RFC/RFT PATCH 0/7] cpu-exec: simplify cpu_exec and rem
From: |
Pavel Dovgalyuk |
Subject: |
Re: [Qemu-devel] [RFC/RFT PATCH 0/7] cpu-exec: simplify cpu_exec and remove some icount special cases |
Date: |
Tue, 31 Jan 2017 12:05:08 +0300 |
Hi, Paolo!
Thanks for refactoring.
I tested these patches with icount record/replay on i386 machine.
It works, but the following changes should be applied.
I also removed call to replay_has_interrupt, because now it is not needed here.
It seems, that this call is an artifact of an older record/replay revision.
diff --git a/cpu-exec.c b/cpu-exec.c
index 3838eb8..5cef8bc 100644
--- a/cpu-exec.c
+++ b/cpu-exec.c
@@ -519,7 +519,8 @@ static inline bool cpu_handle_interrupt(CPUState *cpu,
}
/* Finally, check if we need to exit to the main loop. */
- if (unlikely(atomic_read(&cpu->exit_request) || replay_has_interrupt())) {
+ if (unlikely(atomic_read(&cpu->exit_request)
+ || (use_icount && cpu->icount_decr.u16.low + cpu->icount_extra == 0)))
{
atomic_set(&cpu->exit_request, 0);
cpu->exception_index = EXCP_INTERRUPT;
return true;
Pavel Dovgalyuk
> -----Original Message-----
> From: Paolo Bonzini [mailto:address@hidden On Behalf Of Paolo Bonzini
> Sent: Monday, January 30, 2017 12:09 AM
> To: address@hidden
> Cc: address@hidden; address@hidden; address@hidden
> Subject: [RFC/RFT PATCH 0/7] cpu-exec: simplify cpu_exec and remove some
> icount special cases
>
> The series includes three parts:
>
> 1-2: fix two bugs, the first one pretty bad, the second seems
> to be theoretical only.
>
> 3-5: simplify cpu_exec. This builds on Sergey's conversion
> of cpu_exec to a simple top-down logic, making the phases
> clearer and saving on the cost of siglongjmp in the meanwhile.
>
> 6-7: these are intended to be a base for Pavel's record/replay
> fixes. The main thing I noticed while reviewing is that icount
> is redoing (with u16.high) a lot of things that tcg_exit_req is
> doing too. This is because, at the time icount was introduced,
> tcg_exit_req didn't exist and QEMU instead unwound chained TBs
> through POSIX signals. But now we have essentially two ways to
> do the same thing with subtly different invariants or downright
> bugs (such as the one fixed by patch 1). Patch 6 therefore
> unifies tcg_exit_req and the icount interrupt flag. It saves a
> handful of instructions per TB in icount mode and generally
> makes icount mode "less special", which is a good thing since
> no one seems to understand it well. Patch 7 then removes another
> EXCP_INTERRUPT/cpu_loop_exit pair; by exiting to main loop simply
> through cpu->exit_request, hopefully it fixes one of the issues that
> Pavel was seeing.
>
> For now I've tested this only on an aarch64 Linux image (with
> and without -icount). Thanks,
>
> Paolo
>
> Paolo Bonzini (7):
> cpu-exec: fix jmp_first out-of-bounds access with icount
> cpu-exec: tighten barrier on TCG_EXIT_REQUESTED
> cpu-exec: avoid cpu_loop_exit in cpu_handle_interrupt
> cpu-exec: avoid repeated sigsetjmp on interrupts
> cpu-exec: remove outermost infinite loop
> cpu-exec: unify icount_decr and tcg_exit_req
> cpu-exec: centralize exiting to the main loop
>
> cpu-exec.c | 153
> +++++++++++++++++++++-------------------------
> include/exec/exec-all.h | 1 +
> include/exec/gen-icount.h | 53 ++++++++--------
> include/qom/cpu.h | 15 +++--
> qom/cpu.c | 2 +-
> tcg/tcg.h | 1 -
> translate-all.c | 2 +-
> translate-common.c | 13 ++--
> 8 files changed, 109 insertions(+), 131 deletions(-)
>
> --
> 2.9.3
- [Qemu-devel] [RFC/RFT PATCH 0/7] cpu-exec: simplify cpu_exec and remove some icount special cases, Paolo Bonzini, 2017/01/29
- [Qemu-devel] [PATCH 2/7] cpu-exec: tighten barrier on TCG_EXIT_REQUESTED, Paolo Bonzini, 2017/01/29
- [Qemu-devel] [PATCH 1/7] cpu-exec: fix jmp_first out-of-bounds access with icount, Paolo Bonzini, 2017/01/29
- [Qemu-devel] [PATCH 5/7] cpu-exec: remove outermost infinite loop, Paolo Bonzini, 2017/01/29
- [Qemu-devel] [PATCH 4/7] cpu-exec: avoid repeated sigsetjmp on interrupts, Paolo Bonzini, 2017/01/29
- [Qemu-devel] [PATCH 3/7] cpu-exec: avoid cpu_loop_exit in cpu_handle_interrupt, Paolo Bonzini, 2017/01/29
- [Qemu-devel] [PATCH 6/7] cpu-exec: unify icount_decr and tcg_exit_req, Paolo Bonzini, 2017/01/29
- [Qemu-devel] [PATCH 7/7] cpu-exec: centralize exiting to the main loop, Paolo Bonzini, 2017/01/29
- Re: [Qemu-devel] [RFC/RFT PATCH 0/7] cpu-exec: simplify cpu_exec and remove some icount special cases, no-reply, 2017/01/29
- Re: [Qemu-devel] [RFC/RFT PATCH 0/7] cpu-exec: simplify cpu_exec and remove some icount special cases,
Pavel Dovgalyuk <=