Re: [Qemu-devel] [PATCH 40/54] ram: Remove compression_switch and inline its logic

[Juan Quintela <quintela@redhat.com>]

Peter Xu <peterx@redhat.com> wrote:
> On Thu, Apr 06, 2017 at 03:08:59PM +0200, Juan Quintela wrote:
>> We can calculate its value, so not create a varible for it.
>> 
>> Signed-off-by: Juan Quintela <quintela@redhat.com>
>> 
>> --
>> 
>> After Peter and Dave review, I dropped the variable and just inlined
>> the condition.
>> 
>> Later, Juan.
>> 
>> Signed-off-by: Juan Quintela <quintela@redhat.com>
>> ---
>>  migration/ram.c | 12 ++++++++----
>>  1 file changed, 8 insertions(+), 4 deletions(-)
>> 
>> diff --git a/migration/ram.c b/migration/ram.c
>> index 14d54fd..5dfc9bd 100644
>> --- a/migration/ram.c
>> +++ b/migration/ram.c
>> @@ -336,7 +336,6 @@ static QemuCond comp_done_cond;
>>  /* The empty QEMUFileOps will be used by file in CompressParam */
>>  static const QEMUFileOps empty_ops = { };
>>  
>> -static bool compression_switch;
>>  static DecompressParam *decomp_param;
>>  static QemuThread *decompress_threads;
>>  static QemuMutex decomp_done_lock;
>> @@ -420,7 +419,6 @@ void migrate_compress_threads_create(void)
>>      if (!migrate_use_compression()) {
>>          return;
>>      }
>> -    compression_switch = true;
>>      thread_count = migrate_compress_threads();
>>      compress_threads = g_new0(QemuThread, thread_count);
>>      comp_param = g_new0(CompressParam, thread_count);
>> @@ -1092,7 +1090,6 @@ static bool find_dirty_block(RAMState *rs, PageSearchStatus *pss,
>>                   * point. In theory, xbzrle can do better than compression.
>>                   */
>>                  flush_compressed_data(rs);
>> -                compression_switch = false;
>>              }
>>          }
>>          /* Didn't find anything this time, but try again on the new block */
>> @@ -1326,7 +1323,14 @@ static int ram_save_target_page(RAMState *rs, MigrationState *ms,
>>      /* Check the pages is dirty and if it is send it */
>>      if (migration_bitmap_clear_dirty(rs, dirty_ram_abs)) {
>>          unsigned long *unsentmap;
>> -        if (compression_switch && migrate_use_compression()) {
>> +        /*
>> +         * If xbzrle is on, stop using the data compression after first
>> +         * round of migration even if compression is enabled. In theory,
>> +         * xbzrle can do better than compression.
>> +         */
>> +
>> +        if (migrate_use_compression())
>                                         ^ is this a superfluous ")"?
>

fix compliation. good catch.

I think that I have fixed that in a later patch, as this worked O:-)

>> +            && (rs->ram_bulk_stage || !migrate_use_xbzrle()) {

I need to put it here.

Later, Juan.