Performance regression reported with NFS/RDMA using Omnipath,
bisected to commit e084ee673c ("svcrdma: Add Write chunk WRs to
the RPC's Send WR chain").
Tracing on the server reports:
nfsd-7771 [060] 1758.891809: svcrdma_sq_post_err:
cq.id=205 cid=226 sc_sq_avail=13643/851 status=-12
sq_post_err reports ENOMEM, and the rdma->sc_sq_avail (13643) is
larger than rdma->sc_sq_depth (851). The number of available Send
Queue entries is always supposed to be smaller than the Send Queue
depth. That seems like a Send Queue accounting bug in svcrdma.
As it's getting to be late in the 6.9-rc cycle, revert this commit.
It can be revisited in a subsequent kernel release.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=218743
Fixes: e084ee673c ("svcrdma: Add Write chunk WRs to the RPC's Send WR chain")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
32cf5a4eda