Peter Xu <pet...@redhat.com> wrote:
> On Thu, Mar 23, 2017 at 09:45:30PM +0100, Juan Quintela wrote:
>> Rename it to preffer_xbzrle that is a more descriptive name.
>
> s/preffer/prefer/?
>
>>
>> Signed-off-by: Juan Quintela <quint...@redhat.com>
>> ---
>> migration/ram.c | 9 +++++----
>> 1 file changed, 5 insertions(+), 4 deletions(-)
>>
>> diff --git a/migration/ram.c b/migration/ram.c
>> index 6a39704..591cf89 100644
>> --- a/migration/ram.c
>> +++ b/migration/ram.c
>> @@ -217,6 +217,9 @@ struct RAMState {
>> uint64_t dirty_pages_rate;
>> /* Count of requests incoming from destination */
>> uint64_t postcopy_requests;
>> + /* Should we move to xbzrle after the 1st round
>> + of compression */
>> + bool preffer_xbzrle;
>> /* protects modification of the bitmap */
>> QemuMutex bitmap_mutex;
>> /* Ram Bitmap protected by RCU */
>> @@ -335,7 +338,6 @@ 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;
>> @@ -419,7 +421,6 @@ 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);
>> @@ -1091,7 +1092,7 @@ 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;
>> + rs->preffer_xbzrle = true;
>> }
>> }
>> /* Didn't find anything this time, but try again on the new block */
>> @@ -1323,7 +1324,7 @@ 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 (!rs->preffer_xbzrle && migrate_use_compression()) {
>
> IIUC this prefer_xbzrle can be dynamically calculated by existing
> states:
>
> static inline bool ram_compression_active(RAMState *rs)
> {
> /*
> * 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.
> */
> return migrate_use_compression() && \
> (rs->ram_bulk_stage || !migrate_use_xbzrle());
> }
>
> Then this line can be written as:
>
> if (ram_compression_active(rs)) {
>
> And if so, we can get rid of prefer_xbzrle, right?
>
> Having prefer_xbzrle should be slightly faster though, since it'll at
> least cache the above calculation.
>
> Thanks,
You arrived to the same conclusion than Dave. As it was only used once,
I didn't create the extra function.
I stole your comment verbatim O:-)
Later, Juan.
