[PATCH V3 00/15] use sg helper to operate scatterlist
Ming Lei
ming.lei at redhat.com
Fri Jun 14 02:53:01 UTC 2019
Hi,
Scsi MQ makes a large static allocation for the first scatter gather
list chunk for the driver to use. This is a performance headache we'd
like to fix by reducing the size of the allocation to a 2 element
array. Doing this will break the current guarantee that any driver
using SG_ALL doesn't need to use the scatterlist iterators and can get
away with directly dereferencing the array. Thus we need to update all
drivers to use the scatterlist iterators and remove direct indexing of
the scatterlist array before reducing the initial scatterlist
allocation size in SCSI.
So convert drivers to use scatterlist helper.
There are two types of scsi SGL uses:
1) operate on scsi_sglist(scmd) directly, then one local variable of
'struct scatterlist *' is involved, so the following coccinelle semantic
patch is developed for finding this type of direct sgl uses:
https://marc.info/?l=linux-scsi&m=156031374809852&w=2
2) scsi_sglist(scmd) is stored to cmd->SCp.buffer and the SGL is used
via cmd->SCp.buffer. Simple 'grep SCp.buffer' is used for finding SGL
direct uses, fortunately only the following drivers uses SCp.buffer to
store SGL:
NCR5380, aha152x, arm/, imm, pcmcia, ppa and wd33c93
And arm/ is already ready to handle chained SGL.
The 1st 9 patches are for handling type #1, and the other 6 patches
for handling type #2.
V3:
- update commit log and cover letter, most of words are from
James Bottomley
V2:
- use coccinelle semantic patch for finding direct sgl uses from
scsi command(9 drivers found)
- run 'git grep -E "SCp.buffer"' to find direct sgl uses
from SCp.buffer(6 drivers are found)
Finn Thain (1):
NCR5380: Support chained sg lists
Ming Lei (14):
scsi: vmw_pscsi: use sg helper to operate scatterlist
scsi: advansys: use sg helper to operate scatterlist
scsi: lpfc: use sg helper to operate scatterlist
scsi: mvumi: use sg helper to operate scatterlist
scsi: ipr: use sg helper to operate scatterlist
scsi: pmcraid: use sg helper to operate scatterlist
usb: image: microtek: use sg helper to operate scatterlist
staging: unisys: visorhba: use sg helper to operate scatterlist
s390: zfcp_fc: use sg helper to operate scatterlist
scsi: aha152x: use sg helper to operate scatterlist
scsi: imm: use sg helper to operate scatterlist
scsi: pcmcia: nsp_cs: use sg helper to operate scatterlist
scsi: ppa: use sg helper to operate scatterlist
scsi: wd33c93: use sg helper to operate scatterlist
drivers/s390/scsi/zfcp_fc.c | 4 +-
drivers/scsi/NCR5380.c | 41 ++++++++-----------
drivers/scsi/advansys.c | 2 +-
drivers/scsi/aha152x.c | 29 ++++++++-----
drivers/scsi/imm.c | 2 +-
drivers/scsi/ipr.c | 28 +++++++------
drivers/scsi/lpfc/lpfc_nvmet.c | 3 +-
drivers/scsi/mvumi.c | 9 ++--
drivers/scsi/pcmcia/nsp_cs.c | 4 +-
drivers/scsi/pmcraid.c | 12 +++---
drivers/scsi/ppa.c | 2 +-
drivers/scsi/vmw_pvscsi.c | 2 +-
drivers/scsi/wd33c93.c | 2 +-
.../staging/unisys/visorhba/visorhba_main.c | 9 ++--
drivers/usb/image/microtek.c | 20 ++++-----
drivers/usb/image/microtek.h | 2 +-
16 files changed, 85 insertions(+), 86 deletions(-)
--
2.20.1
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