Patchwork [1/4] migration: set f->is_write and flush in add_to_iovec

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Submitter Paolo Bonzini
Date April 8, 2013, 11:29 a.m.
Message ID <1365420597-5506-2-git-send-email-pbonzini@redhat.com>
Download mbox | patch
Permalink /patch/234741/
State New
Headers show

Comments

Paolo Bonzini - April 8, 2013, 11:29 a.m.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 savevm.c | 25 +++++++++----------------
 1 file changed, 9 insertions(+), 16 deletions(-)
Juan Quintela - April 9, 2013, 11:32 a.m.
Paolo Bonzini <pbonzini@redhat.com> wrote:
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  savevm.c | 25 +++++++++----------------
>  1 file changed, 9 insertions(+), 16 deletions(-)
>
> diff --git a/savevm.c b/savevm.c
> index b1d8988..c952c41 100644
> --- a/savevm.c
> +++ b/savevm.c
> @@ -631,6 +631,11 @@ static void add_to_iovec(QEMUFile *f, const uint8_t *buf, int size)
>          f->iov[f->iovcnt].iov_base = (uint8_t *)buf;
>          f->iov[f->iovcnt++].iov_len = size;
>      }
> +
> +    f->is_write = 1;
> +    if (f->buf_index >= IO_BUF_SIZE || f->iovcnt >= MAX_IOV_SIZE) {
> +        qemu_fflush(f);
> +    }
>  }
>  
>  void qemu_put_buffer_async(QEMUFile *f, const uint8_t *buf, int size)
> @@ -645,14 +650,8 @@ void qemu_put_buffer_async(QEMUFile *f, const uint8_t *buf, int size)
>          abort();
>      }
>  
> -    add_to_iovec(f, buf, size);
> -
> -    f->is_write = 1;
>      f->bytes_xfer += size;
> -
> -    if (f->buf_index >= IO_BUF_SIZE || f->iovcnt >= MAX_IOV_SIZE) {
> -        qemu_fflush(f);
> -    }
> +    add_to_iovec(f, buf, size);
>  }
>  
>  void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size)
> @@ -674,7 +673,6 @@ void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size)
>          if (l > size)
>              l = size;
>          memcpy(f->buf + f->buf_index, buf, l);
> -        f->is_write = 1;
>          f->buf_index += l;

we increase buf_index

>          qemu_put_buffer_async(f, f->buf + (f->buf_index - l), l);

and we call add_to_iovec() here inside.  Notice the torture to get the
old buf_index value.

>          if (qemu_file_get_error(f)) {
> @@ -697,15 +695,10 @@ void qemu_put_byte(QEMUFile *f, int v)
>          abort();
>      }
>  
> -    f->buf[f->buf_index++] = v;
> -    f->is_write = 1;
> +    f->buf[f->buf_index] = v;
>      f->bytes_xfer++;
> -
> -    add_to_iovec(f, f->buf + (f->buf_index - 1), 1);
> -
> -    if (f->buf_index >= IO_BUF_SIZE || f->iovcnt >= MAX_IOV_SIZE) {
> -        qemu_fflush(f);
> -    }
> +    add_to_iovec(f, f->buf + f->buf_index, 1);
> +    f->buf_index++;

And here,  we call add_to_iovec() and then increase buf_index

Is there any good reason for not being consistent?

Once there,  I think that moving the handling of buf_index to inside
add_to_iovec() looks like a good idea?

Later,  Juan.

>  }
>  
>  static void qemu_file_skip(QEMUFile *f, int size)
Paolo Bonzini - April 9, 2013, 11:39 a.m.
Il 09/04/2013 13:32, Juan Quintela ha scritto:
> Paolo Bonzini <pbonzini@redhat.com> wrote:
>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>> ---
>>  savevm.c | 25 +++++++++----------------
>>  1 file changed, 9 insertions(+), 16 deletions(-)
>>
>> diff --git a/savevm.c b/savevm.c
>> index b1d8988..c952c41 100644
>> --- a/savevm.c
>> +++ b/savevm.c
>> @@ -631,6 +631,11 @@ static void add_to_iovec(QEMUFile *f, const uint8_t *buf, int size)
>>          f->iov[f->iovcnt].iov_base = (uint8_t *)buf;
>>          f->iov[f->iovcnt++].iov_len = size;
>>      }
>> +
>> +    f->is_write = 1;
>> +    if (f->buf_index >= IO_BUF_SIZE || f->iovcnt >= MAX_IOV_SIZE) {
>> +        qemu_fflush(f);
>> +    }
>>  }
>>  
>>  void qemu_put_buffer_async(QEMUFile *f, const uint8_t *buf, int size)
>> @@ -645,14 +650,8 @@ void qemu_put_buffer_async(QEMUFile *f, const uint8_t *buf, int size)
>>          abort();
>>      }
>>  
>> -    add_to_iovec(f, buf, size);
>> -
>> -    f->is_write = 1;
>>      f->bytes_xfer += size;
>> -
>> -    if (f->buf_index >= IO_BUF_SIZE || f->iovcnt >= MAX_IOV_SIZE) {
>> -        qemu_fflush(f);
>> -    }
>> +    add_to_iovec(f, buf, size);
>>  }
>>  
>>  void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size)
>> @@ -674,7 +673,6 @@ void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size)
>>          if (l > size)
>>              l = size;
>>          memcpy(f->buf + f->buf_index, buf, l);
>> -        f->is_write = 1;
>>          f->buf_index += l;
> 
> we increase buf_index
> 
>>          qemu_put_buffer_async(f, f->buf + (f->buf_index - l), l);
> 
> and we call add_to_iovec() here inside.  Notice the torture to get the
> old buf_index value.
> 
>>          if (qemu_file_get_error(f)) {
>> @@ -697,15 +695,10 @@ void qemu_put_byte(QEMUFile *f, int v)
>>          abort();
>>      }
>>  
>> -    f->buf[f->buf_index++] = v;
>> -    f->is_write = 1;
>> +    f->buf[f->buf_index] = v;
>>      f->bytes_xfer++;
>> -
>> -    add_to_iovec(f, f->buf + (f->buf_index - 1), 1);
>> -
>> -    if (f->buf_index >= IO_BUF_SIZE || f->iovcnt >= MAX_IOV_SIZE) {
>> -        qemu_fflush(f);
>> -    }
>> +    add_to_iovec(f, f->buf + f->buf_index, 1);
>> +    f->buf_index++;
> 
> And here,  we call add_to_iovec() and then increase buf_index
> 
> Is there any good reason for not being consistent?

The reason is that I didn't want to switch
qemu_put_buffer_async->add_to_iovec in this patch.  I do it in the next one.

> Once there,  I think that moving the handling of buf_index to inside
> add_to_iovec() looks like a good idea?

add_to_iovec() is not called always with something from f->buf.  But it
is a good idea to move this handling of buf_index:

    if (f->buf_index >= IO_BUF_SIZE || f->iovcnt >= MAX_IOV_SIZE) {

out of add_to_iovec.  I do that in patch 4.

Paolo

Patch

diff --git a/savevm.c b/savevm.c
index b1d8988..c952c41 100644
--- a/savevm.c
+++ b/savevm.c
@@ -631,6 +631,11 @@  static void add_to_iovec(QEMUFile *f, const uint8_t *buf, int size)
         f->iov[f->iovcnt].iov_base = (uint8_t *)buf;
         f->iov[f->iovcnt++].iov_len = size;
     }
+
+    f->is_write = 1;
+    if (f->buf_index >= IO_BUF_SIZE || f->iovcnt >= MAX_IOV_SIZE) {
+        qemu_fflush(f);
+    }
 }
 
 void qemu_put_buffer_async(QEMUFile *f, const uint8_t *buf, int size)
@@ -645,14 +650,8 @@  void qemu_put_buffer_async(QEMUFile *f, const uint8_t *buf, int size)
         abort();
     }
 
-    add_to_iovec(f, buf, size);
-
-    f->is_write = 1;
     f->bytes_xfer += size;
-
-    if (f->buf_index >= IO_BUF_SIZE || f->iovcnt >= MAX_IOV_SIZE) {
-        qemu_fflush(f);
-    }
+    add_to_iovec(f, buf, size);
 }
 
 void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size)
@@ -674,7 +673,6 @@  void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size)
         if (l > size)
             l = size;
         memcpy(f->buf + f->buf_index, buf, l);
-        f->is_write = 1;
         f->buf_index += l;
         qemu_put_buffer_async(f, f->buf + (f->buf_index - l), l);
         if (qemu_file_get_error(f)) {
@@ -697,15 +695,10 @@  void qemu_put_byte(QEMUFile *f, int v)
         abort();
     }
 
-    f->buf[f->buf_index++] = v;
-    f->is_write = 1;
+    f->buf[f->buf_index] = v;
     f->bytes_xfer++;
-
-    add_to_iovec(f, f->buf + (f->buf_index - 1), 1);
-
-    if (f->buf_index >= IO_BUF_SIZE || f->iovcnt >= MAX_IOV_SIZE) {
-        qemu_fflush(f);
-    }
+    add_to_iovec(f, f->buf + f->buf_index, 1);
+    f->buf_index++;
 }
 
 static void qemu_file_skip(QEMUFile *f, int size)