sys-block/btrace
btrace can show detailed info about what is happening on a block device io queue.
Screenshots
-
btrace-0.99.3~amd64 ~ppc ~x86doc
View 
Download License: GPL-2
-
btrace-0.0.20071210202527amd64 ppc x86docView Download License: GPL-2
-
btrace-0.0.20070730162628~x86 ~ppc ~amd64docView Download License: GPL-2
-
btrace-0.0.20060614042007~x86 ~ppcdocView Download License: GPL-2
-
btrace-0.0.20060428050322~x86 ~ppcdocView Download License: GPL-2