RE: [PATCH v2] net/filter: Optimize filter_send to coroutine

[Zhang, Chen]

> -----Original Message-----
> From: Rao, Lei <lei.rao@intel.com>
> Sent: Monday, December 27, 2021 9:20 AM
> To: Zhang, Chen <chen.zhang@intel.com>; lizhijian@cn.fujitsu.com;
> jasowang@redhat.com
> Cc: qemu-devel@nongnu.org; Rao, Lei <lei.rao@intel.com>; Li Zhijian
> <lizhijian@fujitsu.com>
> Subject: [PATCH v2] net/filter: Optimize filter_send to coroutine
> 
> 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>
> Reviewed-by: Li Zhijian <lizhijian@fujitsu.com>

Looks good to me.
Reviewed-by: Zhang Chen <chen.zhang@intel.com>

Thanks
Chen

> ---
>  net/filter-mirror.c | 66 ++++++++++++++++++++++++++++++++++++--------
> -
>  1 file changed, 53 insertions(+), 13 deletions(-)
> 
> diff --git a/net/filter-mirror.c b/net/filter-mirror.c index
> f20240cc9f..34a63b5dbb 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 +93,47 @@ 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);
> +    qemu_coroutine_enter(co);
> +
> +    while (!data.done) {
> +        aio_poll(qemu_get_aio_context(), true);
> +    }
> +
> +    return data.ret;
> +}
> +
>  static void redirector_to_filter(NetFilterState *nf,
>                                   const uint8_t *buf,
>                                   int len)
> --
> 2.32.0