Re: [PATCH v3 01/10] migration/dirtyrate: Add get_dirtyrate_thread() function

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Chuan Zheng (zhengchuan@huawei.com) wrote:
> Add get_dirtyrate_thread() functions
> 
> Signed-off-by: Chuan Zheng <zhengchuan@huawei.com>
> Signed-off-by: YanYing Zhuang <ann.zhuangyanying@huawei.com>
> ---
>  migration/Makefile.objs |  1 +
>  migration/dirtyrate.c   | 64 +++++++++++++++++++++++++++++++++++++++++++++++++
>  migration/dirtyrate.h   | 44 ++++++++++++++++++++++++++++++++++
>  3 files changed, 109 insertions(+)
>  create mode 100644 migration/dirtyrate.c
>  create mode 100644 migration/dirtyrate.h
> 
> diff --git a/migration/Makefile.objs b/migration/Makefile.objs
> index 0fc619e..12ae98c 100644
> --- a/migration/Makefile.objs
> +++ b/migration/Makefile.objs
> @@ -6,6 +6,7 @@ common-obj-y += qemu-file.o global_state.o
>  common-obj-y += qemu-file-channel.o
>  common-obj-y += xbzrle.o postcopy-ram.o
>  common-obj-y += qjson.o
> +common-obj-y += dirtyrate.o
>  common-obj-y += block-dirty-bitmap.o
>  common-obj-y += multifd.o
>  common-obj-y += multifd-zlib.o
> diff --git a/migration/dirtyrate.c b/migration/dirtyrate.c
> new file mode 100644
> index 0000000..bb0ebe9
> --- /dev/null
> +++ b/migration/dirtyrate.c
> @@ -0,0 +1,64 @@
> +/*
> + * 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 "qemu/osdep.h"
> +#include "qapi/error.h"
> +#include "crypto/hash.h"
> +#include "crypto/random.h"
> +#include "qemu/config-file.h"
> +#include "exec/memory.h"
> +#include "exec/ramblock.h"
> +#include "exec/target_page.h"
> +#include "qemu/rcu_queue.h"
> +#include "qapi/qapi-commands-migration.h"
> +#include "migration.h"
> +#include "dirtyrate.h"
> +
> +CalculatingDirtyRateState CalculatingState = CAL_DIRTY_RATE_INIT;
> +
> +static int dirty_rate_set_state(int new_state)
> +{
> +    int old_state = CalculatingState;
> +
> +    if (new_state == old_state) {
> +        return -1;
> +    }
> +
> +    if (atomic_cmpxchg(&CalculatingState, old_state, new_state) != old_state) {
> +        return -1;
> +    }

This is a little unusual; this has removed your comment from v1 about
what you're trying to protect; but not quite being clear about what it's
doing.

I think what you want here is closer to migrate_set_state, ie you
pass what you think the old state is, and the state you want to go to.

> +    return 0;
> +}
> +
> +static void calculate_dirtyrate(struct DirtyRateConfig config)
> +{
> +    /* todo */
> +    return;
> +}
> +
> +void *get_dirtyrate_thread(void *arg)
> +{
> +    struct DirtyRateConfig config = *(struct DirtyRateConfig *)arg;
> +    int ret;
> +
> +    ret = dirty_rate_set_state(CAL_DIRTY_RATE_ACTIVE);

so this would become:
    ret = dirty_rate_set_state(CAL_DIRTY_RATE_INIT,
              CAL_DIRTY_RATE_ACTIVE);

> +    if (ret == -1) {
> +        return NULL;
> +    }
> +
> +    calculate_dirtyrate(config);
> +
> +    ret = dirty_rate_set_state(CAL_DIRTY_RATE_END);
> +
> +    return NULL;
> +}
> diff --git a/migration/dirtyrate.h b/migration/dirtyrate.h
> new file mode 100644
> index 0000000..914c363
> --- /dev/null
> +++ b/migration/dirtyrate.h
> @@ -0,0 +1,44 @@
> +/*
> + *  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
> +
> +/*
> + * Sample 256 pages per GB as default.
> + * TODO: Make it configurable.
> + */
> +#define DIRTYRATE_DEFAULT_SAMPLE_PAGES            256
> +
> +/* Take 1s as default for calculation duration */
> +#define DEFAULT_FETCH_DIRTYRATE_TIME_SEC          1
> +
> +struct DirtyRateConfig {
> +    uint64_t sample_pages_per_gigabytes; /* sample pages per GB */
> +    int64_t sample_period_seconds; /* time duration between two sampling */
> +};
> +
> +/*
> + *  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_ACTIVE,
> +    CAL_DIRTY_RATE_END,
> +} CalculatingDirtyRateState;
> +
> +void *get_dirtyrate_thread(void *arg);
> +#endif
> +
> -- 
> 1.8.3.1
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK