Re: [PATCH] net/filter: Optimize filter_send to coroutine

[address@hidden]

On 24/12/2021 10:37, Rao, Lei wrote:
> This patch is to improve the logic of QEMU main thread sleep code in
> qemu_chr_write_buffer() where it can be blocked and can't run other
> coroutines during COLO IO stress test.
>
> Our approach is to put filter_send() in a coroutine. In this way,
> filter_send() will call qemu_coroutine_yield() in qemu_co_sleep_ns(),
> so that it can be scheduled out and QEMU main thread has opportunity to
> run other tasks.
>
> Signed-off-by: Lei Rao <lei.rao@intel.com>
> Signed-off-by: Zhang Chen <chen.zhang@intel.com>
> ---
>   net/filter-mirror.c | 67 ++++++++++++++++++++++++++++++++++++---------
>   1 file changed, 54 insertions(+), 13 deletions(-)
>
> diff --git a/net/filter-mirror.c b/net/filter-mirror.c
> index f20240cc9f..1e9f8b6216 100644
> --- a/net/filter-mirror.c
> +++ b/net/filter-mirror.c
> @@ -20,6 +20,7 @@
>   #include "chardev/char-fe.h"
>   #include "qemu/iov.h"
>   #include "qemu/sockets.h"
> +#include "block/aio-wait.h"
>   
>   #define TYPE_FILTER_MIRROR "filter-mirror"
>   typedef struct MirrorState MirrorState;
> @@ -42,20 +43,21 @@ struct MirrorState {
>       bool vnet_hdr;
>   };
>   
> -static int filter_send(MirrorState *s,
> -                       const struct iovec *iov,
> -                       int iovcnt)
> +typedef struct FilterSendCo {
> +    MirrorState *s;
> +    char *buf;
> +    ssize_t size;
> +    bool done;
> +    int ret;
> +} FilterSendCo;
> +
> +static int _filter_send(MirrorState *s,
> +                       char *buf,
> +                       ssize_t size)
>   {
>       NetFilterState *nf = NETFILTER(s);
>       int ret = 0;
> -    ssize_t size = 0;
>       uint32_t len = 0;
> -    char *buf;
> -
> -    size = iov_size(iov, iovcnt);
> -    if (!size) {
> -        return 0;
> -    }
>   
>       len = htonl(size);
>       ret = qemu_chr_fe_write_all(&s->chr_out, (uint8_t *)&len, sizeof(len));
> @@ -80,10 +82,7 @@ static int filter_send(MirrorState *s,
>           }
>       }
>   
> -    buf = g_malloc(size);
> -    iov_to_buf(iov, iovcnt, 0, buf, size);
>       ret = qemu_chr_fe_write_all(&s->chr_out, (uint8_t *)buf, size);
> -    g_free(buf);
>       if (ret != size) {
>           goto err;
>       }
> @@ -94,6 +93,48 @@ err:
>       return ret < 0 ? ret : -EIO;
>   }
>   
> +static void coroutine_fn filter_send_co(void *opaque)
> +{
> +    FilterSendCo *data = opaque;
> +
> +    data->ret = _filter_send(data->s, data->buf, data->size);
> +    data->done = true;
> +    g_free(data->buf);
> +    aio_wait_kick();
> +}
> +
> +static int filter_send(MirrorState *s,
> +                       const struct iovec *iov,
> +                       int iovcnt)
> +{
> +    ssize_t size = iov_size(iov, iovcnt);
> +    char *buf = NULL;
> +
> +    if (!size) {
> +        return 0;
> +    }
> +
> +    buf = g_malloc(size);
> +    iov_to_buf(iov, iovcnt, 0, buf, size);
> +
> +    FilterSendCo data = {
> +        .s = s,
> +        .size = size,
> +        .buf = buf,
> +        .ret = 0,
> +    };
> +
> +    Coroutine *co = qemu_coroutine_create(filter_send_co, &data);

BTW, does qemu/old gcc complaint such coding style ?

int a;
a = foo()
int b = a;



> +    qemu_coroutine_enter(co);
> +
> +    while (!data.done) {
> +        aio_poll(qemu_get_aio_context(), true);
> +    }
> +
> +    return data.ret;
> +
redundant  newline

Otherwise,
Reviewed-by: Li Zhijian <lizhijian@fujitsu.com>



> +}
> +
>   static void redirector_to_filter(NetFilterState *nf,
>                                    const uint8_t *buf,
>                                    int len)