if a site use php session heavily, the mean problem is too many session file in /tmp. sometime user even can't use 'rm *' delete these too many files.

is it possible add a php session file mapping mechanism?
auto create mapping dir in session_tmp_dir and assign session file into dirs(if dir not created autocreated it)
for example:
mapping session file to 
/tmp/a/a
/tmp/a/b
/tmp/a/c
.....
/tmp/b/a
...

or
/tmp/php_sess/0/0
/tmp/php_sess/0/1
/tmp/php_sess/0/2
/tmp/php_sess/0/3
/tmp/php_sess/0/4
...

user can config, mapping or not mapping session tmp dir,
mapping dir deep level in php.ini....