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author | Gerd Rausch <gerd.rausch@oracle.com> | 2019-06-28 17:31:19 -0700 |
---|---|---|
committer | Santosh Shilimkar <santosh.shilimkar@oracle.com> | 2019-07-09 21:45:41 -0700 |
commit | a55207884708bf1d5b8c87a3c504502de77a5416 (patch) | |
tree | 65b06062d9c6f97fc55c68d15abfc63bc18106a8 /net/rds | |
parent | 616d37a070bb33ea387d0e93343acd8336a30886 (diff) | |
download | linux-a55207884708bf1d5b8c87a3c504502de77a5416.tar.gz linux-a55207884708bf1d5b8c87a3c504502de77a5416.tar.bz2 linux-a55207884708bf1d5b8c87a3c504502de77a5416.zip |
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')
-rw-r--r-- | net/rds/ib.h | 4 | ||||
-rw-r--r-- | net/rds/ib_cm.c | 9 | ||||
-rw-r--r-- | net/rds/ib_frmr.c | 11 |
3 files changed, 8 insertions, 16 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; diff --git a/net/rds/ib_cm.c b/net/rds/ib_cm.c index 66c6eb56072b..8891822eba4f 100644 --- a/net/rds/ib_cm.c +++ b/net/rds/ib_cm.c @@ -460,10 +460,7 @@ static int rds_ib_setup_qp(struct rds_connection *conn) * completion queue and send queue. This extra space is used for FRMR * registration and invalidation work requests */ - fr_queue_space = rds_ibdev->use_fastreg ? - (RDS_IB_DEFAULT_FR_WR + 1) + - (RDS_IB_DEFAULT_FR_INV_WR + 1) - : 0; + fr_queue_space = (rds_ibdev->use_fastreg ? RDS_IB_DEFAULT_FR_WR : 0); /* add the conn now so that connection establishment has the dev */ rds_ib_add_conn(rds_ibdev, conn); @@ -530,7 +527,6 @@ static int rds_ib_setup_qp(struct rds_connection *conn) attr.send_cq = ic->i_send_cq; attr.recv_cq = ic->i_recv_cq; atomic_set(&ic->i_fastreg_wrs, RDS_IB_DEFAULT_FR_WR); - atomic_set(&ic->i_fastunreg_wrs, RDS_IB_DEFAULT_FR_INV_WR); /* * XXX this can fail if max_*_wr is too large? Are we supposed @@ -1009,8 +1005,7 @@ void rds_ib_conn_path_shutdown(struct rds_conn_path *cp) wait_event(rds_ib_ring_empty_wait, rds_ib_ring_empty(&ic->i_recv_ring) && (atomic_read(&ic->i_signaled_sends) == 0) && - (atomic_read(&ic->i_fastreg_wrs) == RDS_IB_DEFAULT_FR_WR) && - (atomic_read(&ic->i_fastunreg_wrs) == RDS_IB_DEFAULT_FR_INV_WR)); + (atomic_read(&ic->i_fastreg_wrs) == RDS_IB_DEFAULT_FR_WR)); tasklet_kill(&ic->i_send_tasklet); tasklet_kill(&ic->i_recv_tasklet); diff --git a/net/rds/ib_frmr.c b/net/rds/ib_frmr.c index 688dcd68d4ea..32ae26ed58a0 100644 --- a/net/rds/ib_frmr.c +++ b/net/rds/ib_frmr.c @@ -239,8 +239,8 @@ static int rds_ib_post_inv(struct rds_ib_mr *ibmr) if (frmr->fr_state != FRMR_IS_INUSE) goto out; - while (atomic_dec_return(&ibmr->ic->i_fastunreg_wrs) <= 0) { - atomic_inc(&ibmr->ic->i_fastunreg_wrs); + while (atomic_dec_return(&ibmr->ic->i_fastreg_wrs) <= 0) { + atomic_inc(&ibmr->ic->i_fastreg_wrs); cpu_relax(); } @@ -257,7 +257,7 @@ static int rds_ib_post_inv(struct rds_ib_mr *ibmr) if (unlikely(ret)) { frmr->fr_state = FRMR_IS_STALE; frmr->fr_inv = false; - atomic_inc(&ibmr->ic->i_fastunreg_wrs); + atomic_inc(&ibmr->ic->i_fastreg_wrs); pr_err("RDS/IB: %s returned error(%d)\n", __func__, ret); goto out; } @@ -285,10 +285,9 @@ 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); } + + atomic_inc(&ic->i_fastreg_wrs); } void rds_ib_unreg_frmr(struct list_head *list, unsigned int *nfreed, |