Hi Krishna,
thanks for debugging this.
please try the following untested patch:
diff --git a/drivers/infiniband/ulp/isert/ib_isert.c
b/drivers/infiniband/ulp/isert/ib_isert.c
index b7df38e..49f5f05 100644
--- a/drivers/infiniband/ulp/isert/ib_isert.c
+++ b/drivers/infiniband/ulp/isert/ib_isert.c
@@ -119,7 +119,7 @@
{
struct isert_device *device = isert_conn->device;
struct ib_qp_init_attr attr;
- int ret;
+ int ret, factor;
memset(&attr, 0, sizeof(struct ib_qp_init_attr));
attr.event_handler = isert_qp_event_callback;
@@ -128,7 +128,9 @@
attr.recv_cq = comp->cq;
attr.cap.max_send_wr = ISERT_QP_MAX_REQ_DTOS + 1;
attr.cap.max_recv_wr = ISERT_QP_MAX_RECV_DTOS + 1;
- attr.cap.max_rdma_ctxs = ISCSI_DEF_XMIT_CMDS_MAX;
+ factor = rdma_rw_mr_factor(device->ib_device, cma_id->port_num,
+ ISCSI_ISER_MAX_SG_TABLESIZE);
+ attr.cap.max_rdma_ctxs = ISCSI_DEF_XMIT_CMDS_MAX * factor;
attr.cap.max_send_sge = device->ib_device->attrs.max_send_sge;
attr.cap.max_recv_sge = 1;
attr.sq_sig_type = IB_SIGNAL_REQ_WR;
diff --git a/drivers/infiniband/ulp/isert/ib_isert.h
b/drivers/infiniband/ulp/isert/ib_isert.h
index 3b296ba..c9ccf1d 100644
--- a/drivers/infiniband/ulp/isert/ib_isert.h
+++ b/drivers/infiniband/ulp/isert/ib_isert.h
@@ -63,7 +63,8 @@
(ISER_RX_PAYLOAD_SIZE + sizeof(u64) + sizeof(struct
ib_sge) + \
sizeof(struct ib_cqe) + sizeof(bool)))
-#define ISCSI_ISER_SG_TABLESIZE 256
+/* Maximum support is 16MB I/O size */
+#define ISCSI_ISER_MAX_SG_TABLESIZE 4096
enum isert_desc_type {
ISCSI_TX_CONTROL,
On 7/7/2020 3:36 PM, Krishnamraju Eraparaju wrote:
Looks like the commit 07173c3e(block: enable multipage bvecs) has
uncovered iSER SQ sizing issue.
Here is how I hit the issue:
Created two luns under single target, then run the below script on each
lun(parallelly).
while [ 1 ]
do
iozone -i 0 -i 1 -I -+d -s 100000 -r 16384 -w
done
Then failures like below are logged in dmesg output, due to iw_cxgb4 SQ
getting full at iSER target.
"isert: isert_rdma_rw_ctx_post: Cmd: 00000000cb75342a failed to post
RDMA res"
This issue won't occur if luns are created on seperate targets.
Also, the issue won't occur if I revert the multipage bvecs(07173c3e)
changes at initator.
Currently SQ is being sized this way:
attr.cap.max_send_wr = ISERT_QP_MAX_REQ_DTOS:138 +1 +
(ISCSI_DEF_XMIT_CMDS_MAX:128 * factor:3) = 523.
I tried increaseing the SQ size and observed that the issue is not
occuring when attr.cap.max_send_wr is 562.
Looks like the avg length of RDMA READ/WRITE operations has increased
after "multipage bvecs" changes.
Queueing many large sized RDMA READ/WRITE WRs may cause backpressure and
increases the chances of SQ getting full at provider driver.
Notice the length(0x7f000 & 0x2000) of each RDMA READ operation below,
for Before and After case.
Before "multipage bvecs" RDMA READ:
[ +0.001903] iser: iscsi_iser_task_xmit: ctask xmit [cid 0 itt 0x78]
[ +0.000007] iser: iser_fast_reg_mr: lkey=0x8a41 rkey=0x8a41
addr=0x446166000 length=0x7f000
[ +0.000000] iser: iser_prepare_read_cmd: Cmd itt:120 READ tags
RKEY:0X8A41 VA:0X446166000
[ +0.000007] iser: iscsi_iser_task_xmit: ctask xmit [cid 0 itt 0x6f]
[ +0.000003] iser: iser_fast_reg_mr: lkey=0x13b51 rkey=0x13b51
addr=0x443b25000 length=0x7f000
[ +0.000001] iser: iser_prepare_read_cmd: Cmd itt:111 READ tags
RKEY:0X13B51 VA:0X443B25000
[ +0.000022] iser: iscsi_iser_task_xmit: ctask xmit [cid 0 itt 0xe]
[ +0.000001] iser: iser_fast_reg_mr: lkey=0xa371 rkey=0xa371
addr=0x4461a4000 length=0x2000
[ +0.000001] iser: iser_prepare_read_cmd: Cmd itt:14 READ tags
RKEY:0XA371 VA:0X4461A4000
[ +0.000004] iser: iscsi_iser_task_xmit: ctask xmit [cid 0 itt 0x79]
[ +0.000003] iser: iser_fast_reg_mr: lkey=0x12f4f rkey=0x12f4f
addr=0x4461a9000 length=0x7f000
[ +0.000001] iser: iser_prepare_read_cmd: Cmd itt:121 READ tags
RKEY:0X12F4F VA:0X4461A9000
[ +0.000005] iser: iscsi_iser_task_xmit: ctask xmit [cid 0 itt 0x7d]
[ +0.000003] iser: iser_fast_reg_mr: lkey=0xe040 rkey=0xe040
addr=0x447e67000 length=0x7f000
[ +0.000001] iser: iser_prepare_read_cmd: Cmd itt:125 READ tags
RKEY:0XE040 VA:0X447E67000
[ +0.000021] iser: iscsi_iser_task_xmit: ctask xmit [cid 0 itt 0x7b]
[ +0.000001] iser: iser_fast_reg_mr: lkey=0xb149 rkey=0xb149
addr=0x3d0366000 length=0x2000
[ +0.000001] iser: iser_prepare_read_cmd: Cmd itt:123 READ tags
RKEY:0XB149 VA:0X3D0366000
[ +0.000004] iser: iscsi_iser_task_xmit: ctask xmit [cid 0 itt 0xb]
[ +0.000003] iser: iser_fast_reg_mr: lkey=0x1014c rkey=0x1014c
addr=0x3d0368000 length=0x7f000
[ +0.000001] iser: iser_prepare_read_cmd: Cmd itt:11 READ tags
RKEY:0X1014C VA:0X3D0368000
[ +0.000007] iser: iscsi_iser_task_xmit: ctask xmit [cid 0 itt 0x62]
[ +0.000003] iser: iser_fast_reg_mr: lkey=0x7c3b rkey=0x7c3b
addr=0x3d03e7000 length=0x7f000
[ +0.000001] iser: iser_prepare_read_cmd: Cmd itt:98 READ tags
RKEY:0X7C3B VA:0X3D03E7000
[ +0.000021] iser: iscsi_iser_task_xmit: ctask xmit [cid 0 itt 0x11]
[ +0.000001] iser: iser_fast_reg_mr: lkey=0x11752 rkey=0x11752
addr=0x3d6de6000 length=0x2000
[ +0.000001] iser: iser_prepare_read_cmd: Cmd itt:17 READ tags
RKEY:0X11752 VA:0X3D6DE6000
[ +0.000004] iser: iscsi_iser_task_xmit: ctask xmit [cid 0 itt 0x77]
After "multipage bvecs" RDMA READ:
[ +0.002455] iser: iscsi_iser_task_xmit: ctask xmit [cid 0 itt 0x7d]
[ +0.000006] iser: iser_fast_reg_mr: lkey=0x7991 rkey=0x7991
addr=0x3d2819000 length=0x7f000
[ +0.000001] iser: iser_prepare_read_cmd: Cmd itt:125 READ tags
RKEY:0X7991 VA:0X3D2819000
[ +0.000005] iser: iscsi_iser_task_xmit: ctask xmit [cid 0 itt 0x7e]
[ +0.000003] iser: iser_fast_reg_mr: lkey=0x8c9b rkey=0x8c9b
addr=0x3d2898000 length=0x7f000
[ +0.000000] iser: iser_prepare_read_cmd: Cmd itt:126 READ tags
RKEY:0X8C9B VA:0X3D2898000
[ +0.000003] iser: iscsi_iser_task_xmit: ctask xmit [cid 0 itt 0x7f]
[ +0.000003] iser: iser_fast_reg_mr: lkey=0x856d rkey=0x856d
addr=0x3d2917000 length=0x7f000
[ +0.000000] iser: iser_prepare_read_cmd: Cmd itt:127 READ tags
RKEY:0X856D VA:0X3D2917000
[ +0.000004] iser: iscsi_iser_task_xmit: ctask xmit [cid 0 itt 0x1]
[ +0.000002] iser: iser_fast_reg_mr: lkey=0x9b55 rkey=0x9b55
addr=0x3d2999000 length=0x7f000
[ +0.000001] iser: iser_prepare_read_cmd: Cmd itt:1 READ tags
RKEY:0X9B55 VA:0X3D2999000
[ +0.000003] iser: iscsi_iser_task_xmit: ctask xmit [cid 0 itt 0x2]
[ +0.000002] iser: iser_fast_reg_mr: lkey=0x86cf rkey=0x86cf
addr=0x3d2018000 length=0x7f000
[ +0.000000] iser: iser_prepare_read_cmd: Cmd itt:2 READ tags
RKEY:0X86CF VA:0X3D2018000
[ +0.000003] iser: iscsi_iser_task_xmit: ctask xmit [cid 0 itt 0x3]
[ +0.000003] iser: iser_fast_reg_mr: lkey=0x8062 rkey=0x8062
addr=0x3d2097000 length=0x7f000
[ +0.000000] iser: iser_prepare_read_cmd: Cmd itt:3 READ tags
RKEY:0X8062 VA:0X3D2097000
[ +0.000003] iser: iscsi_iser_task_xmit: ctask xmit [cid 0 itt 0x4]
[ +0.000002] iser: iser_fast_reg_mr: lkey=0xc34b rkey=0xc34b
addr=0x3d2116000 length=0x7f000
[ +0.000000] iser: iser_prepare_read_cmd: Cmd itt:4 READ tags
RKEY:0XC34B VA:0X3D2116000
[ +0.000003] iser: iscsi_iser_task_xmit: ctask xmit [cid 0 itt 0x5]
[ +0.000002] iser: iser_fast_reg_mr: lkey=0x8b6d rkey=0x8b6d
addr=0x3d2195000 length=0x7f000
[ +0.000001] iser: iser_prepare_read_cmd: Cmd itt:5 READ tags
RKEY:0X8B6D VA:0X3D2195000
[ +0.000003] iser: iscsi_iser_task_xmit: ctask xmit [cid 0 itt 0x6]
[ +0.000002] iser: iser_fast_reg_mr: lkey=0xce56 rkey=0xce56
addr=0x3d0e14000 length=0x7f000
[ +0.000000] iser: iser_prepare_read_cmd: Cmd itt:6 READ tags
RKEY:0XCE56 VA:0X3D0E14000
[ +0.000003] iser: iscsi_iser_task_xmit: ctask xmit [cid 0 itt 0x7]
[ +0.000002] iser: iser_fast_reg_mr: lkey=0xba45 rkey=0xba45
addr=0x3d0e93000 length=0x7f000
[ +0.000001] iser: iser_prepare_read_cmd: Cmd itt:7 READ tags
RKEY:0XBA45 VA:0X3D0E93000
[ +0.000002] iser: iscsi_iser_task_xmit: ctask xmit [cid 0 itt 0x8]
Hence, I feel iSER target SQ is undersized and needs to be sized
properly to hold max possible entries. I might be wrong.
Please take a look.
Thanks,
Krishna.
