From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37399) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Xmhyg-0006y5-Iq for qemu-devel@nongnu.org; Fri, 07 Nov 2014 06:45:23 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Xmhyb-0001Cg-Tj for qemu-devel@nongnu.org; Fri, 07 Nov 2014 06:45:18 -0500 Received: from [2001:41d0:8:2b42::1] (port=34503 helo=greensocs.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Xmhyb-0001Al-DB for qemu-devel@nongnu.org; Fri, 07 Nov 2014 06:45:13 -0500 Message-ID: <545CB0C5.5080107@greensocs.com> Date: Fri, 07 Nov 2014 12:45:09 +0100 From: Frederic Konrad MIME-Version: 1.0 References: <20141107103123.6136.18545.stgit@PASHA-ISP> <20141107103207.6136.22294.stgit@PASHA-ISP> <545CAAC0.7060904@redhat.com> <003b01cffa7f$06618a40$13249ec0$@Dovgaluk@ispras.ru> In-Reply-To: <003b01cffa7f$06618a40$13249ec0$@Dovgaluk@ispras.ru> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFC PATCH v4 07/25] icount: implement icount requesting List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Pavel Dovgaluk , 'Paolo Bonzini' , qemu-devel@nongnu.org Cc: peter.maydell@linaro.org, peter.crosthwaite@xilinx.com, alex.bennee@linaro.org, mark.burton@greensocs.com, real@ispras.ru, batuzovk@ispras.ru, maria.klimushenkova@ispras.ru, afaerber@suse.de On 07/11/2014 12:36, Pavel Dovgaluk wrote: >> From: Paolo Bonzini [mailto:pbonzini@redhat.com] >> On 07/11/2014 11:32, Pavel Dovgalyuk wrote: >>> Replay uses number of executed instructions to determine corrent events >>> injection moments. This patch introduces new function for querying the >>> instructions counter. >>> >>> Signed-off-by: Pavel Dovgalyuk >>> --- >>> cpus.c | 26 +++++++++++++++++++++++--- >>> include/qemu/timer.h | 1 + >>> 2 files changed, 24 insertions(+), 3 deletions(-) >>> >>> diff --git a/cpus.c b/cpus.c >>> index 7e8c507..2ec6d75 100644 >>> --- a/cpus.c >>> +++ b/cpus.c >>> @@ -136,8 +136,7 @@ typedef struct TimersState { >>> >>> static TimersState timers_state; >>> >>> -/* Return the virtual CPU time, based on the instruction counter. */ >>> -static int64_t cpu_get_icount_locked(void) >>> +static int64_t cpu_get_instructions_counter_locked(void) >>> { >>> int64_t icount; >>> CPUState *cpu = current_cpu; >>> @@ -145,10 +144,31 @@ static int64_t cpu_get_icount_locked(void) >>> icount = timers_state.qemu_icount; >>> if (cpu) { >>> if (!cpu_can_do_io(cpu)) { >>> - fprintf(stderr, "Bad clock read\n"); >>> + fprintf(stderr, "Bad icount read\n"); >>> + exit(1); >>> } >>> icount -= (cpu->icount_decr.u16.low + cpu->icount_extra); >>> } >>> + return icount; >>> +} >>> + >>> +int64_t cpu_get_instructions_counter(void) >>> +{ >>> + /* This function calls are synchnonized to timer changes, >>> + calling cpu_get_instructions_counter_locked without lock is safe */ >>> + int64_t icount = timers_state.qemu_icount; >>> + CPUState *cpu = current_cpu; >>> + >>> + if (cpu) { >>> + icount -= (cpu->icount_decr.u16.low + cpu->icount_extra); >>> + } >>> + return icount; >>> +} >> This is the same as Frederic's QEMU_CLOCK_ICOUNT clock, right? Any >> reason why one is better than the other? > Not really. Frederic's QEMU_CLOCK_ICOUNT is measured in nanoseconds. > And this counter is measured in instructions. > > Pavel Dovgalyuk > So you transformed your implementation to use icount? I didn't saw that in the cover letter. I guess you replay event's according to the current instruction? I implemented icount clock with the QEMUTimer API so a callback can be notified during the replay at the right instruction. By the way do you have a git tree somewhere where I can get the patches? Fred