Hi, Since supporting to blk-mq, big pre-allocation for sg list is introduced, this way is very unfriendly wrt. memory consumption. There were Red Hat internal reports that some scsi_debug based tests can't be run any more because of too big pre-allocation. Also lpfc users commplained that 1GB+ ram is pre-allocatd for single HBA. The two patches try to address this issue by allocating sg list runtime, meantime pre-allocating one or two inline sg entries for small IO. This ways follows NVMe's approach wrt. sg list allocation. V2: - move inline sg table initializetion into one helper - introduce new helper for getting inline sg - comment log fix Ming Lei (2): scsi: core: avoid to pre-allocate big chunk for protection meta data scsi: core: avoid to pre-allocate big chunk for sg list drivers/scsi/scsi_lib.c | 78 ++++++++++++++++++++++++++++++++++--------------- 1 file changed, 55 insertions(+), 23 deletions(-) Cc: Christoph Hellwig <hch@xxxxxx> Cc: Bart Van Assche <bvanassche@xxxxxxx> Cc: Ewan D. Milne <emilne@xxxxxxxxxx> Cc: Hannes Reinecke <hare@xxxxxxxx> -- 2.9.5
