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Re: [Qemu-devel] [PATCH v6 11/14] target/arm: PMU: Add instruction and c
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [PATCH v6 11/14] target/arm: PMU: Add instruction and cycle events |
Date: |
Wed, 17 Oct 2018 14:12:21 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 |
On 10/17/18 12:47 PM, Aaron Lindsay wrote:
> On Oct 16 17:04, Richard Henderson wrote:
>> On 10/10/18 1:37 PM, Aaron Lindsay wrote:
>>> + * Return the underlying cycle count for the PMU cycle counters. If we're
>>> in
>>> + * usermode, simply return 0.
>>> + */
>>> +static uint64_t cycles_get_count(CPUARMState *env)
>>> +{
>>> +#ifndef CONFIG_USER_ONLY
>>> + return muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL),
>>> + ARM_CPU_FREQ, NANOSECONDS_PER_SECOND);
>>> +#else
>>> + return 0;
>>> +#endif
>>> +}
>>
>> Usually we pass through the host cycle counter.
>> See cpu_get_host_ticks().
>
> Why do you prefer cpu_get_host_ticks()? And are you suggesting this for
> just user-mode, or both system and user?
Just user-mode. Providing a clock with unknown scaling is more useful than a
constant 0.
r~
- Re: [Qemu-devel] [PATCH v6 12/14] target/arm: PMU: Set PMCR.N to 4, (continued)
- Re: [Qemu-devel] [PATCH v6 12/14] target/arm: PMU: Set PMCR.N to 4, Richard Henderson, 2018/10/16
- Re: [Qemu-devel] [PATCH v6 12/14] target/arm: PMU: Set PMCR.N to 4, Aaron Lindsay, 2018/10/17
- Re: [Qemu-devel] [PATCH v6 12/14] target/arm: PMU: Set PMCR.N to 4, Richard Henderson, 2018/10/17
- Re: [Qemu-devel] [PATCH v6 12/14] target/arm: PMU: Set PMCR.N to 4, Aaron Lindsay, 2018/10/17
- Re: [Qemu-devel] [PATCH v6 12/14] target/arm: PMU: Set PMCR.N to 4, Richard Henderson, 2018/10/17
- Re: [Qemu-devel] [PATCH v6 12/14] target/arm: PMU: Set PMCR.N to 4, Peter Maydell, 2018/10/18
[Qemu-devel] [PATCH v6 14/14] target/arm: Send interrupts on PMU counter overflow, Aaron Lindsay, 2018/10/10
[Qemu-devel] [PATCH v6 11/14] target/arm: PMU: Add instruction and cycle events, Aaron Lindsay, 2018/10/10
[Qemu-devel] [PATCH v6 10/14] target/arm: Finish implementation of PM[X]EVCNTR and PM[X]EVTYPER, Aaron Lindsay, 2018/10/10
[Qemu-devel] [PATCH v6 13/14] target/arm: Implement PMSWINC, Aaron Lindsay, 2018/10/10
Re: [Qemu-devel] [PATCH v6 00/14] More fully implement ARM PMUv3, Peter Maydell, 2018/10/16