> -----Original Message----- > From: Sagi Grimberg [mailto:sagig@xxxxxxxxxxxxxxxxxx] > Sent: Tuesday, July 07, 2015 1:27 AM > To: Steve Wise; dledford@xxxxxxxxxx > Cc: infinipath@xxxxxxxxx; sagig@xxxxxxxxxxxx; ogerlitz@xxxxxxxxxxxx; roid@xxxxxxxxxxxx; linux-rdma@xxxxxxxxxxxxxxx; > eli@xxxxxxxxxxxx; target-devel@xxxxxxxxxxxxxxx > Subject: Re: [PATCH V5 3/5] RDMA/iser: Limit sg tablesize and max_sectors to device fastreg max depth > > On 7/6/2015 5:35 PM, Steve Wise wrote: > > > > > >> -----Original Message----- > >> From: Sagi Grimberg [mailto:sagig@xxxxxxxxxxxxxxxxxx] > >> Sent: Monday, July 06, 2015 2:51 AM > >> To: Steve Wise; dledford@xxxxxxxxxx > >> Cc: infinipath@xxxxxxxxx; sagig@xxxxxxxxxxxx; ogerlitz@xxxxxxxxxxxx; roid@xxxxxxxxxxxx; linux-rdma@xxxxxxxxxxxxxxx; > >> eli@xxxxxxxxxxxx; target-devel@xxxxxxxxxxxxxxx > >> Subject: Re: [PATCH V5 3/5] RDMA/iser: Limit sg tablesize and max_sectors to device fastreg max depth > >> > >> On 7/5/2015 8:44 PM, Steve Wise wrote: > >>> Currently the sg tablesize, which dictates fast register page list > >>> depth to use, does not take into account the limits of the rdma device. > >>> So adjust it once we discover the device fastreg max depth limit. Also > >>> adjust the max_sectors based on the resulting sg tablesize. > >>> > >>> Signed-off-by: Steve Wise <swise@xxxxxxxxxxxxxxxxxxxxx> > >>> --- > >>> > >>> drivers/infiniband/ulp/iser/iscsi_iser.c | 9 +++++++++ > >>> 1 files changed, 9 insertions(+), 0 deletions(-) > >>> > >>> diff --git a/drivers/infiniband/ulp/iser/iscsi_iser.c b/drivers/infiniband/ulp/iser/iscsi_iser.c > >>> index 6a594aa..de8730d 100644 > >>> --- a/drivers/infiniband/ulp/iser/iscsi_iser.c > >>> +++ b/drivers/infiniband/ulp/iser/iscsi_iser.c > >>> @@ -640,6 +640,15 @@ iscsi_iser_session_create(struct iscsi_endpoint *ep, > >>> SHOST_DIX_GUARD_CRC); > >>> } > >>> > >>> + /* > >>> + * Limit the sg_tablesize and max_sectors based on the device > >>> + * max fastreg page list length. > >>> + */ > >>> + shost->sg_tablesize = min_t(unsigned short, shost->sg_tablesize, > >>> + ib_conn->device->dev_attr.max_fast_reg_page_list_len); > >>> + shost->max_sectors = min_t(unsigned int, > >>> + 1024, (shost->sg_tablesize * PAGE_SIZE) >> 9); > >>> + > >> > >> The min statement is meaningless for max_sectors - you do a min between > >> default sg_tablesize and frpl length - so the maximum sg_tablesize is > >> 128 which is 1024 max_sectors. > > > > I'm not following. What if ib_conn->device->dev_attr.max_fast_reg_page_list_len is say, 32? > > Then shost->sg_tablesize is set to 32, and max_sectors is set to (32*4K) >> 9 == 256 512B sectors. > > Correct - but it cannot exceed 1024 (as it is derived from sg_tablesize > which is maximum 128). Actually it is initialized to 1024 in iscsi_iser_sht / iscsi_iser.c, so it isn't derived from sg_tables (although it probably should be). I can remove the min_t() though. Hey Or, thoughts? Steve. -- To unsubscribe from this list: send the line "unsubscribe target-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
