tree 9240283c872e0c110c0fef2e424180fc62bed487
parent 5543c72e2bbb30e5ba5938b18ec26617b8b3fb04
author Chris Leech <christopher.leech@intel.com> 1260467966 -0800
committer James Bottomley <James.Bottomley@suse.de> 1260657033 -0600

[SCSI] libfc: reduce hold time on SCSI host lock

Introduce a new lock to protect the list of fc_fcp_pkt structs in libfc
instead of using the host lock.  This reduces the contention of this heavily
used lock, and I see up to a 25% performance gain in CPU bound small I/O
tests when scaling out across multiple quad-core CPUs.

The big win is in removing the host lock from the completion path
completely, as it does not need to be held around the call to scsi_done.

Signed-off-by: Chris Leech <christopher.leech@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>