The host lock is a serious scalability problem on 2-socket and larger systems which are doing a lot of I/O. Before removing the temporary usgae of DEF_SCSI_QCMD, we need to remove all uses of serial_number.
An unrelated performance issue is that reusing the most recent driver-specific data structure to track the I/O instead of the least recently used keeps the cache-hot lines in use, which is a nice performance improvement. It's already present in the mpt3sas driver, it just didn't make it into the fusion or mpt2sas drivers yet. Matthew Wilcox (7): mpt3sas: Remove uses of serial_number mpt3sas: Remove use of DEF_SCSI_QCMD mpt2sas: Remove uses of serial_number mpt2sas: Remove use of DEF_SCSI_QCMD mpt2sas: Add free smids to the head, not tail of list fusion: Add free msg frames to the head, not tail of list fusion: Remove use of DEF_SCSI_QCMD drivers/message/fusion/mptbase.c | 2 +- drivers/message/fusion/mptfc.c | 12 +++++------- drivers/message/fusion/mptsas.c | 10 ++++------ drivers/message/fusion/mptscsih.c | 8 +++----- drivers/message/fusion/mptscsih.h | 2 +- drivers/message/fusion/mptspi.c | 12 +++++------- drivers/scsi/mpt2sas/mpt2sas_base.c | 8 ++++---- drivers/scsi/mpt2sas/mpt2sas_base.h | 2 +- drivers/scsi/mpt2sas/mpt2sas_ctl.c | 2 +- drivers/scsi/mpt2sas/mpt2sas_scsih.c | 24 +++++++++--------------- drivers/scsi/mpt3sas/mpt3sas_base.h | 2 +- drivers/scsi/mpt3sas/mpt3sas_ctl.c | 2 +- drivers/scsi/mpt3sas/mpt3sas_scsih.c | 24 +++++++++--------------- 13 files changed, 45 insertions(+), 65 deletions(-) -- 1.9.0 -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
