Comment 3 for bug 952920

I got the following conflict when applying the patch:

patch -Np1 < /tmp/deadlock_detect_switch.diff
patching file storage/innobase/handler/ha_innodb.cc
Hunk #1 succeeded at 111 (offset 1 line).
Hunk #2 succeeded at 12387 (offset 252 lines).
Hunk #3 succeeded at 12914 (offset 298 lines).
Hunk #4 succeeded at 12945 (offset 301 lines).
patching file storage/innobase/lock/lock0lock.c
Hunk #1 succeeded at 377 (offset 1 line).
Hunk #2 succeeded at 1812 (offset 2 lines).
Hunk #3 succeeded at 3822 (offset 3 lines).
patching file mysql-test/suite/sys_vars/t/deadlock_detect_basic.test
patching file mysql-test/suite/sys_vars/t/max_purge_size_basic.test
patching file storage/innobase/srv/srv0srv.c
Hunk #1 succeeded at 548 (offset 3 lines).
Hunk #2 succeeded at 3966 (offset 70 lines).
patching file mysql-test/r/percona_server_variables_release.result
Hunk #1 succeeded at 97 (offset 1 line).
Hunk #2 FAILED at 129.
1 out of 2 hunks FAILED -- saving rejects to file mysql-test/r/percona_server_variables_release.result.rej
patching file mysql-test/suite/sys_vars/r/all_vars.result
Hunk #1 succeeded at 14 (offset -1 lines).

Now, that reject file is:

--- mysql-test/r/percona_server_variables_release.result
+++ mysql-test/r/percona_server_variables_release.result
@@ -129,6 +130,7 @@
 INNODB_LOG_GROUP_HOME_DIR
 INNODB_MAX_DIRTY_PAGES_PCT
 INNODB_MAX_PURGE_LAG
+INNODB_MAX_PURGE_SIZE
 INNODB_MIRRORED_LOG_GROUPS
 INNODB_OLD_BLOCKS_PCT
 INNODB_OLD_BLOCKS_TIME

That brings me to the question:

Why do you have INNODB_MAX_PURGE_SIZE when same effect can be accomplished with innodb-purge-batch-size. The batch determines the number of records purged by trx_purge. Can you elaborate on this?