Mostly Chinese Will mix with Chinese ,Malay will mix with Malay and Indian will mix with Indian.
It depends .
The Malay are made up majority ,Indian come second,Chinese are the least among the local,in Bentong they are less than 70 ,this numbers are from Feb To March 2018..
The Indonesians made up the largest foreigners ,followed by Bangladesh ,Myanmar and Vietnamese.
The are more mainland Chinese girls in Bentong prison compare to local Chinese,mostly Mainland Chinese are involved in Prostitute in Genting Highland.
Benny the Chinese orang Kerja leader told me ,he a VIP prisoners.All jailer in Bentong know him ,he close with all gang and cops.
Kajang jail law are tougher than Bentong jail.
I don't know about Sg Buloh,but I heard Benny said mostly rich and VIP prisoners will went to Sg Buloh.