rigth way to find free space on log segment

-- Server information

-- Adaptive Server Enterprise/15.0.3/EBF 17690 ESD#1.1 RELSE/P/Solaris AMD64/OS 5.10/ase1503/2681/64-bit/FBO/Thu Aug 20 15:37:40 2009

Good afternoon,

I tried the following command to find out the free space in the log segment

1.dbcc checktable(syslogs)

2.sp_helpsegment logsegment

3.select data_pages(db_id('DB_NAME'),8,0)

4.sp_spaceused syslogs

solution 1/2/4 give about the same result but solution 1 might be long to compute when the log segment is full.

How do you efficiently compute free space in log segment?

Thanks all

Simon