From b1092d9002fec323aaaf42dcbff88b2f46d4f3d5 Mon Sep 17 00:00:00 2001
From: Olaf Kirch <[EMAIL PROTECTED]>
Date: Thu, 24 Apr 2008 00:27:34 -0700
Subject: [PATCH] mthca/mlx4: avoid recycling old FMR R_Keys too soon
When a FMR is unmapped, mthca and mlx4 reset the map count to 0, and
clear the upper part of the R_Key which is used as the sequence counter.
This poses a problem for RDS, which uses ib_fmr_unmap as a fence
operation. RDS assumes that after issuing an unmap, the old R_Keys
will be invalid for a "reasonable" period of time. For instance, Oracle
processes uses shared memory buffers allocated from a pool of buffers.
When a process dies, we want to reclaim these buffers - but we must make sure
there are no pending RDMA operations to/from those buffers.
The only way to achieve that is by using unmap and sync the TPT.
However, when the sequence count is reset on unmap, there is a high
likelihood that a new mapping will be given the same R_Key that was
issued a few milliseconds ago.
To prevent this, we suggest to not reset the sequence count when
unmapping a FMR.
Signed-off-by: Olaf Kirch <[EMAIL PROTECTED]>
---
drivers/infiniband/hw/mthca/mthca_mr.c | 13 -------------
drivers/net/mlx4/mr.c | 6 ------
2 files changed, 0 insertions(+), 19 deletions(-)
diff --git a/drivers/infiniband/hw/mthca/mthca_mr.c
b/drivers/infiniband/hw/mthca/mthca_mr.c
index aa6c70a..e4f83cb 100644
--- a/drivers/infiniband/hw/mthca/mthca_mr.c
+++ b/drivers/infiniband/hw/mthca/mthca_mr.c
@@ -814,15 +814,9 @@ int mthca_arbel_map_phys_fmr(struct ib_fmr *ibfmr, u64
*page_list,
void mthca_tavor_fmr_unmap(struct mthca_dev *dev, struct mthca_fmr *fmr)
{
- u32 key;
-
if (!fmr->maps)
return;
- key = tavor_key_to_hw_index(fmr->ibmr.lkey);
- key &= dev->limits.num_mpts - 1;
- fmr->ibmr.lkey = fmr->ibmr.rkey = tavor_hw_index_to_key(key);
-
fmr->maps = 0;
writeb(MTHCA_MPT_STATUS_SW, fmr->mem.tavor.mpt);
@@ -830,16 +824,9 @@ void mthca_tavor_fmr_unmap(struct mthca_dev *dev, struct
mthca_fmr *fmr)
void mthca_arbel_fmr_unmap(struct mthca_dev *dev, struct mthca_fmr *fmr)
{
- u32 key;
-
if (!fmr->maps)
return;
- key = arbel_key_to_hw_index(fmr->ibmr.lkey);
- key &= dev->limits.num_mpts - 1;
- key = adjust_key(dev, key);
- fmr->ibmr.lkey = fmr->ibmr.rkey = arbel_hw_index_to_key(key);
-
fmr->maps = 0;
*(u8 *) fmr->mem.arbel.mpt = MTHCA_MPT_STATUS_SW;
diff --git a/drivers/net/mlx4/mr.c b/drivers/net/mlx4/mr.c
index 0c05a10..b9e57b0 100644
--- a/drivers/net/mlx4/mr.c
+++ b/drivers/net/mlx4/mr.c
@@ -602,15 +602,9 @@ EXPORT_SYMBOL_GPL(mlx4_fmr_enable);
void mlx4_fmr_unmap(struct mlx4_dev *dev, struct mlx4_fmr *fmr,
u32 *lkey, u32 *rkey)
{
- u32 key;
-
if (!fmr->maps)
return;
- key = key_to_hw_index(fmr->mr.key);
- key &= dev->caps.num_mpts - 1;
- *lkey = *rkey = fmr->mr.key = hw_index_to_key(key);
-
fmr->maps = 0;
*(u8 *) fmr->mpt = MLX4_MPT_STATUS_SW;
--
1.5.4.rc3
--
Olaf Kirch | --- o --- Nous sommes du soleil we love when we play
[EMAIL PROTECTED] | / | \ sol.dhoop.naytheet.ah kin.ir.samse.qurax
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