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.
sg_alloc_table_chained() is improved to support variant size of 1st
pre-allocated SGL in the 1st patch as suggested by Christoph.
The other 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.
V3:
- improve sg_alloc_table_chained() to accept variant size of
the 1st pre-allocated SGL
- applies the improved sg API to address the big pre-allocation
issue
V2:
- move inline sg table initializetion into one helper
- introduce new helper for getting inline sg
- comment log fix
Ming Lei (3):
lib/sg_pool.c: improve APIs for allocating sg pool
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 | 36 +++++++++++++++++++++++----------
include/linux/scatterlist.h | 27 ++++++++++++++++++++-----
lib/scatterlist.c | 36 +++++++++++++++++++++------------
lib/sg_pool.c | 49 ++++++++++++++++++++++++++++++---------------
4 files changed, 103 insertions(+), 45 deletions(-)
Cc: Christoph Hellwig <h...@lst.de>
Cc: Bart Van Assche <bvanass...@acm.org>
Cc: Ewan D. Milne <emi...@redhat.com>
Cc: Hannes Reinecke <h...@suse.com>
--
2.9.5
