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authorGerd Rausch <gerd.rausch@oracle.com>2019-06-28 17:31:19 -0700
committerSantosh Shilimkar <santosh.shilimkar@oracle.com>2019-07-09 21:45:41 -0700
commita55207884708bf1d5b8c87a3c504502de77a5416 (patch)
tree65b06062d9c6f97fc55c68d15abfc63bc18106a8 /net/rds/ib.h
parent616d37a070bb33ea387d0e93343acd8336a30886 (diff)
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Revert "RDS: IB: split the mr registration and invalidation path"
This reverts commit 56012459310a1dbcc55c2dbf5500a9f7571402cb. RDS kept spinning inside function "rds_ib_post_reg_frmr", waiting for "i_fastreg_wrs" to become incremented: while (atomic_dec_return(&ibmr->ic->i_fastreg_wrs) <= 0) { atomic_inc(&ibmr->ic->i_fastreg_wrs); cpu_relax(); } Looking at the original commit: commit 56012459310a ("RDS: IB: split the mr registration and invalidation path") In there, the "rds_ib_mr_cqe_handler" was changed in the following way: void rds_ib_mr_cqe_handler(struct rds_ib_connection *ic, struct ib_wc *wc) if (frmr->fr_inv) { frmr->fr_state = FRMR_IS_FREE; frmr->fr_inv = false; atomic_inc(&ic->i_fastreg_wrs); } else { atomic_inc(&ic->i_fastunreg_wrs); } It looks like it's got it exactly backwards: Function "rds_ib_post_reg_frmr" keeps track of the outstanding requests via "i_fastreg_wrs". Function "rds_ib_post_inv" keeps track of the outstanding requests via "i_fastunreg_wrs" (post original commit). It also sets: frmr->fr_inv = true; However the completion handler "rds_ib_mr_cqe_handler" adjusts "i_fastreg_wrs" when "fr_inv" had been true, and adjusts "i_fastunreg_wrs" otherwise. The original commit was done in the name of performance: to remove the performance bottleneck No performance benefit could be observed with a fixed-up version of the original commit measured between two Oracle X7 servers, both equipped with Mellanox Connect-X5 HCAs. The prudent course of action is to revert this commit. Signed-off-by: Gerd Rausch <gerd.rausch@oracle.com> Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Diffstat (limited to 'net/rds/ib.h')
-rw-r--r--net/rds/ib.h4
1 files changed, 1 insertions, 3 deletions
diff --git a/net/rds/ib.h b/net/rds/ib.h
index 67a715b076ca..66c03c7665b2 100644
--- a/net/rds/ib.h
+++ b/net/rds/ib.h
@@ -15,8 +15,7 @@
#define RDS_IB_DEFAULT_RECV_WR 1024
#define RDS_IB_DEFAULT_SEND_WR 256
-#define RDS_IB_DEFAULT_FR_WR 256
-#define RDS_IB_DEFAULT_FR_INV_WR 256
+#define RDS_IB_DEFAULT_FR_WR 512
#define RDS_IB_DEFAULT_RETRY_COUNT 1
@@ -157,7 +156,6 @@ struct rds_ib_connection {
/* To control the number of wrs from fastreg */
atomic_t i_fastreg_wrs;
- atomic_t i_fastunreg_wrs;
/* interrupt handling */
struct tasklet_struct i_send_tasklet;