We already have trace_svcrdma_decode_rseg(), which records each
ingress Read segment. Instead of reporting those again when they
are about to be posted as RDMA Reads, let's fire one tracepoint
before posting each type of chunk.
So we'll get:
nfsd-1998 [002] 321.666615: svcrdma_decode_rseg: cq.id=4 cid=42 segno=0 position=0 192@0x013ca9ebfae14000:0xb0010b05
nfsd-1998 [002] 321.666615: svcrdma_decode_rseg: cq.id=4 cid=42 segno=1 position=0 7688@0x013ca9ebf914e000:0xb0010a05
nfsd-1998 [002] 321.666615: svcrdma_decode_rseg: cq.id=4 cid=42 segno=2 position=0 28@0x013ca9ebfae15000:0xb0010905
nfsd-1998 [002] 321.666622: svcrdma_decode_rqst: cq.id=4 cid=42 xid=0x013ca9eb vers=1 credits=128 proc=RDMA_NOMSG hdrlen=100
nfsd-1998 [002] 321.666642: svcrdma_post_read_chunk: cq.id=3 cid=112 sqecount=3
kworker/2:1H-221 [002] 321.673949: svcrdma_wc_read: cq.id=3 cid=112 status=SUCCESS (0/0x0)
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Refactor: svc_rdma_map_reply_msg() is restructured to DMA map only
the parts of rq_res that do not contain a result payload.
This change has been tested to confirm that it does not cause a
regression in the no Write chunk and single Write chunk cases.
Multiple Write chunks have not been tested.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
When counting the number of SGEs needed to construct a Send request,
do not count result payloads. And, when copying the Reply message
into the pull-up buffer, result payloads are not to be copied to the
Send buffer.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Refactor: Instead of re-parsing the ingress RPC Call transport
header when constructing the egress RPC Reply transport header, use
the new parsed Write list and Reply chunk, which are version-
agnostic and already XDR decoded.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Refactor: Instead of re-parsing the ingress RPC Call transport
header when constructing RDMA Writes, use the new parsed chunk lists
for the Write list and Reply chunk, which are version-agnostic and
already XDR-decoded.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
The only RPC/RDMA ordering requirement between RDMA Writes and RDMA
Sends is that the responder must post the Writes on the Send queue
before posting the Send that conveys the RPC Reply for that Write
payload.
The Linux NFS server implementation now has a transport method that
can post result Payload Writes earlier than svc_rdma_sendto:
->xpo_result_payload()
This gets RDMA Writes going earlier so they are more likely to be
complete at the remote end before the Send completes.
Some care must be taken with pulled-up Replies. We don't want to
push the Write chunk and then send the same payload data via Send.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Have the NFSD encoders annotate the boundaries of every
direct-data-placement eligible result data payload. Then change
svcrdma to use that annotation instead of the xdr->page_len
when handling Write chunks.
For NFSv4 on RDMA, that enables the ability to recognize multiple
result payloads per compound. This is a pre-requisite for supporting
multiple Write chunks per RPC transaction.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Clean up: "result payload" is a less confusing name for these
payloads. "READ payload" reflects only the NFS usage.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This was discovered using O_DIRECT at the client side, with small
unaligned file offsets or IOs that span multiple file pages.
Fixes: e248aa7be8 ("svcrdma: Remove max_sge check at connect time")
Signed-off-by: Dan Aloni <dan@kernelim.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Jason tells me that a ULP cannot rely on getting an ESTABLISHED
and DISCONNECTED event pair for each connection, so transport
reference counting in the CM event handler will never be reliable.
Now that we have ib_drain_qp(), svcrdma should no longer need to
hold transport references while Sends and Receives are posted. So
remove the get/put call sites in the CM event handlers.
This eliminates a significant source of locked memory bus traffic.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
First, refactor: Dereference the svc_rdma_send_ctxt inside
svc_rdma_send() instead of at every call site.
Then, it can be passed into trace_svcrdma_post_send() to get the
proper completion ID.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Set up a completion ID in each svc_rdma_send_ctxt. The ID is used
to match an incoming Send completion to a transport and to a
previous ib_post_send().
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
- Use the _err naming convention instead
- Remove display of kernel memory address of the controlling xprt
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Like svc_rdma_send_error(), have svc_rdma_send_error_msg() handle
any error conditions internally, rather than duplicating that
recovery logic at every call site.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
The common "send RDMA_ERR" function should be in svc_rdma_sendto.c,
since that is where the other Send-related functions are located.
So from here, I will beef up svc_rdma_send_error_msg() and deprecate
svc_rdma_send_error().
A generic svc_rdma_send_error_msg() will need to handle both
ERR_CHUNK and ERR_VERS. Copy that logic from svc_rdma_send_error()
to svc_rdma_send_error_msg().
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Another step towards making svc_rdma_send_error_msg() and
svc_rdma_send_error() similar enough to eliminate one of them.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Commit 4757d90b15 ("svcrdma: Report Write/Reply chunk overruns")
made an effort to preserve I/O pages until RDMA Write completion.
In a subsequent patch, I intend to de-duplicate the two functions
that send ERR_CHUNK responses. Pull the save_io_pages() call out of
svc_rdma_send_error_msg() to make it more like
svc_rdma_send_error().
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
It appears that the RPC/RDMA transport does not need serialization
of calls to its xpo_sendto method. Move the mutex into the socket
methods that still need that serialization.
Tail latencies are unambiguously better with this patch applied.
fio randrw 8KB 70/30 on NFSv3, smaller numbers are better:
clat percentiles (usec):
With xpt_mutex:
r | 99.99th=[ 8848]
w | 99.99th=[ 9634]
Without xpt_mutex:
r | 99.99th=[ 8586]
w | 99.99th=[ 8979]
Serializing the construction of RPC/RDMA transport headers is not
really necessary at this point, because the Linux NFS server
implementation never changes its credit grant on a connection. If
that should change, then svc_rdma_sendto will need to serialize
access to the transport's credit grant fields.
Reported-by: kbuild test robot <lkp@intel.com>
[ cel: fix uninitialized variable warning ]
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Utilize the xpo_release_rqst transport method to ensure that each
rqstp's svc_rdma_recv_ctxt object is released even when the server
cannot return a Reply for that rqstp.
Without this fix, each RPC whose Reply cannot be sent leaks one
svc_rdma_recv_ctxt. This is a 2.5KB structure, a 4KB DMA-mapped
Receive buffer, and any pages that might be part of the Reply
message.
The leak is infrequent unless the network fabric is unreliable or
Kerberos is in use, as GSS sequence window overruns, which result
in connection loss, are more common on fast transports.
Fixes: 3a88092ee3 ("svcrdma: Preserve Receive buffer until svc_rdma_sendto")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
On some platforms, DMA mapping part of a page is more costly than
copying bytes. Indeed, not involving the I/O MMU can help the
RPC/RDMA transport scale better for tiny I/Os across more RDMA
devices. This is because interaction with the I/O MMU is eliminated
for each of these small I/Os. Without the explicit unmapping, the
NIC no longer needs to do a costly internal TLB shoot down for
buffers that are just a handful of bytes.
Since pull-up is now a more a frequent operation, I've introduced a
trace point in the pull-up path. It can be used for debugging or
user-space tools that count pull-up frequency.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Performance optimization: Avoid syncing the transport buffer twice
when Reply buffer pull-up is necessary.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Same idea as the receive-side changes I did a while back: use
xdr_stream helpers rather than open-coding the XDR chunk list
encoders. This builds the Reply transport header from beginning to
end without backtracking.
As additional clean-ups, fill in documenting comments for the XDR
encoders and sprinkle some trace points in the new encoding
functions.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Preparing for subsequent patches, no behavior change expected.
Pass the RPC Call's svc_rdma_recv_ctxt deeper into the sendto()
path. This enables passing more information about Requester-
provided Write and Reply chunks into those lower-level functions.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Preparing for subsequent patches, no behavior change expected.
Pass the RPC Call's svc_rdma_recv_ctxt deeper into the sendto()
path. This enables passing more information about Requester-
provided Write and Reply chunks into those lower-level functions.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Preparing for subsequent patches, no behavior change expected.
Pass the RPC Call's svc_rdma_recv_ctxt deeper into the sendto()
path. This enables passing more information about Requester-
provided Write and Reply chunks into the lower-level send
functions.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Cache the locations of the Requester-provided Write list and Reply
chunk so that the Send path doesn't need to parse the Call header
again.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Introduce a helper function to compute the XDR pad size of a
variable-length XDR object.
Clean up: Replace open-coded calculation of XDR pad sizes.
I'm sure I haven't found every instance of this calculation.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This error path is almost never executed. Found by code inspection.
Fixes: 99722fe4d5 ("svcrdma: Persistently allocate and DMA-map Send buffers")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
svcrdma expects that the payload falls precisely into the xdr_buf
page vector. This does not seem to be the case for
nfsd4_encode_readv().
This code is called only when fops->splice_read is missing or when
RQ_SPLICE_OK is clear, so it's not a noticeable problem in many
common cases.
Add new transport method: ->xpo_read_payload so that when a READ
payload does not fit exactly in rq_res's page vector, the XDR
encoder can inform the RPC transport exactly where that payload is,
without the payload's XDR pad.
That way, when a Write chunk is present, the transport knows what
byte range in the Reply message is supposed to be matched with the
chunk.
Note that the Linux NFS server implementation of NFS/RDMA can
currently handle only one Write chunk per RPC-over-RDMA message.
This simplifies the implementation of this fix.
Fixes: b042098063 ("nfsd4: allow exotic read compounds")
Buglink: https://bugzilla.kernel.org/show_bug.cgi?id=198053
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Capture the total size of Sends, the size of DMA map and the
matching DMA unmap to ensure operation is correct.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
These can result in a lot of log noise, and are able to be triggered
by client misbehavior. Since there are trace points in these
handlers now, there's no need to spam the log.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Two and a half years ago, the client was changed to use gathered
Send for larger inline messages, in commit 655fec6987 ("xprtrdma:
Use gathered Send for large inline messages"). Several fixes were
required because there are a few in-kernel device drivers whose
max_sge is 3, and these were broken by the change.
Apparently my memory is going, because some time later, I submitted
commit 25fd86eca1 ("svcrdma: Don't overrun the SGE array in
svc_rdma_send_ctxt"), and after that, commit f3c1fd0ee2 ("svcrdma:
Reduce max_send_sges"). These too incorrectly assumed in-kernel
device drivers would have more than a few Send SGEs available.
The fix for the server side is not the same. This is because the
fundamental problem on the server is that, whether or not the client
has provisioned a chunk for the RPC reply, the server must squeeze
even the most complex RPC replies into a single RDMA Send. Failing
in the send path because of Send SGE exhaustion should never be an
option.
Therefore, instead of failing when the send path runs out of SGEs,
switch to using a bounce buffer mechanism to handle RPC replies that
are too complex for the device to send directly. That allows us to
remove the max_sge check to enable drivers with small max_sge to
work again.
Reported-by: Don Dutile <ddutile@redhat.com>
Fixes: 25fd86eca1 ("svcrdma: Don't overrun the SGE array in ...")
Cc: stable@vger.kernel.org
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
xpo_prep_reply_hdr are not used now.
It was defined for tcp transport only, however it cannot be
called indirectly, so let's move it to its caller and
remove unused callback.
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
o Select the R_key to invalidate while the CPU cache still contains
the received RPC Call transport header, rather than waiting until
we're about to send the RPC Reply.
o Choose Send With Invalidate if there is exactly one distinct R_key
in the received transport header. If there's more than one, the
client will have to perform local invalidation after it has
already waited for remote invalidation.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
missing Chuck's fixes for the problem with callbacks over GSS from
multi-homed servers, and a smaller fix from Laura Abbott.
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Merge tag 'nfsd-4.19-1' of git://linux-nfs.org/~bfields/linux
Pull nfsd updates from Bruce Fields:
"Chuck Lever fixed a problem with NFSv4.0 callbacks over GSS from
multi-homed servers.
The only new feature is a minor bit of protocol (change_attr_type)
which the client doesn't even use yet.
Other than that, various bugfixes and cleanup"
* tag 'nfsd-4.19-1' of git://linux-nfs.org/~bfields/linux: (27 commits)
sunrpc: Add comment defining gssd upcall API keywords
nfsd: Remove callback_cred
nfsd: Use correct credential for NFSv4.0 callback with GSS
sunrpc: Extract target name into svc_cred
sunrpc: Enable the kernel to specify the hostname part of service principals
sunrpc: Don't use stack buffer with scatterlist
rpc: remove unneeded variable 'ret' in rdma_listen_handler
nfsd: use true and false for boolean values
nfsd: constify write_op[]
fs/nfsd: Delete invalid assignment statements in nfsd4_decode_exchange_id
NFSD: Handle full-length symlinks
NFSD: Refactor the generic write vector fill helper
svcrdma: Clean up Read chunk path
svcrdma: Avoid releasing a page in svc_xprt_release()
nfsd: Mark expected switch fall-through
sunrpc: remove redundant variables 'checksumlen','blocksize' and 'data'
nfsd: fix leaked file lock with nfs exported overlayfs
nfsd: don't advertise a SCSI layout for an unsupported request_queue
nfsd: fix corrupted reply to badly ordered compound
nfsd: clarify check_op_ordering
...
svc_xprt_release() invokes svc_free_res_pages(), which releases
pages between rq_respages and rq_next_page.
Historically, the RPC/RDMA transport has set these two pointers to
be different by one, which means:
- one page gets released when svc_recv returns 0. This normally
happens whenever one or more RDMA Reads need to be dispatched to
complete construction of an RPC Call.
- one page gets released after every call to svc_send.
In both cases, this released page is immediately refilled by
svc_alloc_arg. There does not seem to be a reason for releasing this
page.
To avoid this unnecessary memory allocator traffic, set rq_next_page
more carefully.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Instead of declaring and passing a dummy 'bad_wr' pointer, pass NULL
as third argument to ib_post_(send|recv|srq_recv)().
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Acked-by: Anna Schumaker <Anna.Schumaker@netapp.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
While sending each RPC Reply, svc_rdma_sendto allocates and DMA-
maps a separate buffer where the RPC/RDMA transport header is
constructed. The buffer is unmapped and released in the Send
completion handler. This is significant per-RPC overhead,
especially for small RPCs.
Instead, allocate and DMA-map a buffer, and cache it in each
svc_rdma_send_ctxt. This buffer and its mapping can be re-used
for each RPC, saving the cost of memory allocation and DMA
mapping.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Clean up: No current caller of svc_rdma_send's passes in a chained
WR. The logic that counts the chain length can be replaced with a
constant (1).
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Clean up: Now that the send_wr is part of the svc_rdma_send_ctxt,
svc_rdma_post_send_wr is nearly empty.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Receive buffers are always the same size, but each Send WR has a
variable number of SGEs, based on the contents of the xdr_buf being
sent.
While assembling a Send WR, keep track of the number of SGEs so that
we don't exceed the device's maximum, or walk off the end of the
Send SGE array.
For now the Send path just fails if it exceeds the maximum.
The current logic in svc_rdma_accept bases the maximum number of
Send SGEs on the largest NFS request that can be sent or received.
In the transport layer, the limit is actually based on the
capabilities of the underlying device, not on properties of the
Upper Layer Protocol.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
svc_rdma_op_ctxt's are pre-allocated and maintained on a per-xprt
free list. This eliminates the overhead of calling kmalloc / kfree,
both of which grab a globally shared lock that disables interrupts.
Introduce a replacement to svc_rdma_op_ctxt's that is built
especially for the svcrdma Send path.
Subsequent patches will take advantage of this new structure by
allocating real resources which are then cached in these objects.
The allocations are freed when the transport is torn down.
I've renamed the structure so that static type checking can be used
to ensure that uses of op_ctxt and send_ctxt are not confused. As an
additional clean up, structure fields are renamed to conform with
kernel coding conventions.
Additional clean ups:
- Handle svc_rdma_send_ctxt_get allocation failure at each call
site, rather than pre-allocating and hoping we guessed correctly
- All send_ctxt_put call-sites request page freeing, so remove
the @free_pages argument
- All send_ctxt_put call-sites unmap SGEs, so fold that into
svc_rdma_send_ctxt_put
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Clean up: Since there's already a svc_rdma_op_ctxt being passed
around with the running count of mapped SGEs, drop unneeded
parameters to svc_rdma_post_send_wr().
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Clean up: svc_rdma_dma_map_buf does mostly the same thing as
svc_rdma_dma_map_page, so let's fold these together.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
The current Receive path uses an array of pages which are allocated
and DMA mapped when each Receive WR is posted, and then handed off
to the upper layer in rqstp::rq_arg. The page flip releases unused
pages in the rq_pages pagelist. This mechanism introduces a
significant amount of overhead.
So instead, kmalloc the Receive buffer, and leave it DMA-mapped
while the transport remains connected. This confers a number of
benefits:
* Each Receive WR requires only one receive SGE, no matter how large
the inline threshold is. This helps the server-side NFS/RDMA
transport operate on less capable RDMA devices.
* The Receive buffer is left allocated and mapped all the time. This
relieves svc_rdma_post_recv from the overhead of allocating and
DMA-mapping a fresh buffer.
* svc_rdma_wc_receive no longer has to DMA unmap the Receive buffer.
It has to DMA sync only the number of bytes that were received.
* svc_rdma_build_arg_xdr no longer has to free a page in rq_pages
for each page in the Receive buffer, making it a constant-time
function.
* The Receive buffer is now plugged directly into the rq_arg's
head[0].iov_vec, and can be larger than a page without spilling
over into rq_arg's page list. This enables simplification of
the RDMA Read path in subsequent patches.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Chuck Lever
Dan Aloni
Vasily Averin
Linus Torvalds
Bart Van Assche