Re: [RFC PATCH 1/8] migration/dirtyrate: Add get_dirtyrate_thread() function

[Zheng Chuan]

On 2020/8/5 0:23, Dr. David Alan Gilbert wrote:
> * Chuan Zheng (zhengchuan@huawei.com) wrote:
>> From: Zheng Chuan <zhengchuan@huawei.com>
>>
>> Add get_dirtyrate_thread() functions
>>
>> Signed-off-by: Zheng Chuan <zhengchuan@huawei.com>
>> Signed-off-by: YanYing Zhang <ann.zhuangyanying@huawei.com>
>> ---
>>  migration/dirtyrate.c | 63 
>> +++++++++++++++++++++++++++++++++++++++++++++++++++
>>  migration/dirtyrate.h | 38 +++++++++++++++++++++++++++++++
>>  2 files changed, 101 insertions(+)
>>  create mode 100644 migration/dirtyrate.c
>>  create mode 100644 migration/dirtyrate.h
>>
>> diff --git a/migration/dirtyrate.c b/migration/dirtyrate.c
>> new file mode 100644
>> index 0000000..fc652fb
>> --- /dev/null
>> +++ b/migration/dirtyrate.c
>> @@ -0,0 +1,63 @@
>> +/*
>> + * Dirtyrate implement code
>> + *
>> + * Copyright (c) 2017-2020 HUAWEI TECHNOLOGIES CO.,LTD.
>> + *
>> + * Authors:
>> + *  Chuan Zheng <zhengchuan@huawei.com>
>> + *
>> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
>> + * See the COPYING file in the top-level directory.
>> + */
>> +
>> +#include "dirtyrate.h"
>> +
>> +static uint64_t sample_pages_per_gigabytes = DIRTYRATE_DEFAULT_SAMPLE_PAGES;
>> +static uint64_t dirty_rate; /* MB/s */
>> +CalculatingDirtyRateStage calculating_dirty_rate_stage = 
>> CAL_DIRTY_RATE_INIT;
>> +
>> +static bool calculate_dirtyrate(struct dirtyrate_config config,
>> +                        uint64_t *dirty_rate, int64_t time)
>> +{
>> +    /* todo */
>> +    return true;
> 
> It would be better to make this return false until you fill it in!
> 
Sure, I'll fix that in V2.
>> +}
>> +
>> +static void set_dirty_rate(uint64_t drate)
>> +{
>> +    dirty_rate = drate;
>> +}
>> +
>> +/*
>> + * There are multithread will write/read *calculating_dirty_rate_stage*,
>> + * we can protect only one thread write/read it by libvirt api.
>> + * So we don't add mutex_lock to protect it here, but we must calculate
>> + * dirty_rate by libvirt api.
>> + */
>> +static void set_dirty_rate_stage(CalculatingDirtyRateStage ratestage)
>> +{
>> +    calculating_dirty_rate_stage = ratestage;
>> +}
> 
> I don't think I understand the threading comment here; when you say the
> 'libvirt api' do youmean QMP?  Maybe you could do this with an
> atomic_cmpxchg like we do in migrate_set_state?
> 
Yes, I mean QMP, atomic_cmpxchg should be better:)
I'll fix that and make comments more clear in V2.

>> +
>> +void *get_dirtyrate_thread(void *arg)
>> +{
>> +    struct dirtyrate_config config = *(struct dirtyrate_config *)arg;
>> +    uint64_t dirty_rate;
>> +    uint64_t hash_dirty_rate;
>> +    bool query_succ;
>> +    int64_t msec = 0;
>> + 
>> +    set_dirty_rate_stage(CAL_DIRTY_RATE_ING);
>> +
>> +    query_succ = calculate_dirtyrate(config, &hash_dirty_rate, msec);
>> +    if (!query_succ) {
>> +        dirty_rate = 0;
>> +    } else {
>> +        dirty_rate = hash_dirty_rate;
>> +    }
>> +
>> +    set_dirty_rate(dirty_rate);
>> +    set_dirty_rate_stage(CAL_DIRTY_RATE_END);
>> +
>> +    return NULL;
>> +}
>> diff --git a/migration/dirtyrate.h b/migration/dirtyrate.h
>> new file mode 100644
>> index 0000000..9a5c228
>> --- /dev/null
>> +++ b/migration/dirtyrate.h
>> @@ -0,0 +1,38 @@
>> +/*
>> + *  Dirtyrate common functions
>> + *
>> + *  Copyright (c) 2020 HUAWEI TECHNOLOGIES CO., LTD.
>> + *
>> + *  Authors:
>> + *  Chuan Zheng <zhengchuan@huawei.com>
>> + *
>> + *  This work is licensed under the terms of the GNU GPL, version 2 or 
>> later.
>> + *  See the COPYING file in the top-level directory.
>> + */
>> +
>> +#ifndef QEMU_MIGRATION_DIRTYRATE_H
>> +#define QEMU_MIGRATION_DIRTYRATE_H
>> +
>> +/* take 256 pages per GB for cal dirty rate */
>> +#define DIRTYRATE_DEFAULT_SAMPLE_PAGES    256
>> +
>> +struct dirtyrate_config {
>> +    uint64_t sample_pages_per_gigabytes;
>> +    int64_t sample_period_seconds;
>> +};
>> +
>> +/*
>> + *  To record calculate dirty_rate status:
>> + *  0: initial status, calculating thread is not be created here.
>> + *  1: calculating thread is created.
>> + *  2: calculating thread is end, we can get result.
>> + */
>> +typedef enum {
>> +    CAL_DIRTY_RATE_INIT  = 0,
>> +    CAL_DIRTY_RATE_ING   = 1,
> 
> I'm not sure why ING?
Maybe ACTIVE is better, i'll fix that.
> 
> 
>> +    CAL_DIRTY_RATE_END   = 2,
>> +} CalculatingDirtyRateStage;
>> +
>> +void *get_dirtyrate_thread(void *arg);
>> +#endif
>> +
>> -- 
>> 1.8.3.1
>>
> --
> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
> 
> 
> .
>