Similar to r300836, r301800, and r302550, cl and ct will always
be non-NULL as they're allocated using the mem_alloc routines,
which always use `malloc(..., M_WAITOK)`.
MFC after: 1 week
Reported by: Coverity
CID: 1007342
Sponsored by: EMC / Isilon Storage Division
Similar to r300836 and r301800, cl and cu will always be non-NULL as they're
allocated using the mem_alloc routines, which always use
`malloc(..., M_WAITOK)`.
Deobfuscating the cleanup path fixes a leak where if cl was NULL and
cu was not, cu would not be free'd, and also removes a duplicate test for
cl not being NULL.
MFC after: 1 week
Reported by: Coverity
CID: 1007033, 1007344
Sponsored by: EMC / Isilon Storage Division
Similar to r300836, cl and ct will always be non-NULL as they're allocated
using the mem_alloc routines, which always use `malloc(..., M_WAITOK)`.
Deobfuscating the cleanup path fixes a leak where if cl was NULL and
ct was not, ct would not be free'd, and also removes a duplicate test for
cl not being NULL.
Approved by: re (gjb)
Differential Revision: https://reviews.freebsd.org/D6801
MFC after: 1 week
Reported by: Coverity
CID: 1229999
Reviewed by: cem
Sponsored by: EMC / Isilon Storage Division
Both cd and xprt will be non-NULL after their respective malloc(9) wrappers are
called (mem_alloc and svc_xprt_alloc, which calls mem_alloc) as mem_alloc
always gets called with M_WAITOK|M_ZERO today. Thus, testing for them being
non-NULL is incorrect -- it misleads Coverity and it misleads the reader.
Remove some unnecessary NULL initializations as a follow up to help solidify
the fact that these pointers will be initialized properly in sys/rpc/.. with
the interfaces the way they are currently.
Differential Revision: https://reviews.freebsd.org/D6572
MFC after: 2 weeks
Reported by: Coverity
CID: 1007338, 1007339, 1007340
Reviewed by: markj, truckman
Sponsored by: EMC / Isilon Storage Division
The mem_alloc macro calls calloc (userspace) / malloc(.., M_WAITOK|M_ZERO)
under the covers, so zeroing out memory is already handled by the underlying
calls
MFC after: 1 week
Sponsored by: EMC / Isilon Storage Division
'buf.value' was previously treated as a nul-terminated string, but only
allocated with strlen() space. Rectify this.
Reported by: Coverity
CID: 1007639
Sponsored by: EMC / Isilon Storage Division
sosend(). The only release on the xp_snt_cnt is done after sosend(),
with an intent to synchronize with load_acq in svc_vc_ack().
Reviewed by: alc
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
implementation.
The kernel RPC code, which is responsible for the low-level scheduling
of incoming NFS requests, contains a throttling mechanism that
prevents too much kernel memory from being tied up by NFS requests
that are being serviced. When the throttle is engaged, the RPC layer
stops servicing incoming NFS sockets, resulting ultimately in
backpressure on the clients (if they're using TCP). However, this is
a very heavy-handed mechanism as it prevents all clients from making
any requests, regardless of how heavy or light they are. (Thus, when
engaged, the throttle often prevents clients from even mounting the
filesystem.) The throttle mechanism applies specifically to requests
that have been received by the RPC layer (from a TCP or UDP socket)
and are queued waiting to be serviced by one of the nfsd threads; it
does not limit the amount of backlog in the socket buffers.
The original implementation limited the total bytes of queued requests
to the minimum of a quarter of (nmbclusters * MCLBYTES) and 45 MiB.
The former limit seems reasonable, since requests queued in the socket
buffers and replies being constructed to the requests in progress will
all require some amount of network memory, but the 45 MiB limit is
plainly ridiculous for modern memory sizes: when running 256 service
threads on a busy server, 45 MiB would result in just a single
maximum-sized NFS3PROC_WRITE queued per thread before throttling.
Removing this limit exposed integer-overflow bugs in the original
computation, and related bugs in the routines that actually account
for the amount of traffic enqueued for service threads. The old
implementation also attempted to reduce accounting overhead by
batching updates until each queue is fully drained, but this is prone
to livelock, resulting in repeated accumulate-throttle-drain cycles on
a busy server. Various data types are changed to long or unsigned
long; explicit 64-bit types are not used due to the unavailability of
64-bit atomics on many 32-bit platforms, but those platforms also
cannot support nmbclusters large enough to cause overflow.
This code (in a 10.1 kernel) is presently running on production NFS
servers at CSAIL.
Summary of this revision:
* Removes 45 MiB limit on requests queued for nfsd service threads
* Fixes integer-overflow and signedness bugs
* Avoids unnecessary throttling by not deferring accounting for
completed requests
Differential Revision: https://reviews.freebsd.org/D2165
Reviewed by: rmacklem, mav
MFC after: 30 days
Relnotes: yes
Sponsored by: MIT Computer Science & Artificial Intelligence Laboratory
feature is to quisce the system before suspend.
Stop is implemented by reusing the thread_single(9) with the special
mode SINGLE_ALLPROC. SINGLE_ALLPROC differs from the existing
single-threading modes by allowing (requiring) caller to operate on
other process. Interruptible sleeps for !TDF_SBDRY threads are
suspended like SIGSTOP does it, instead of aborting the sleep, like
SINGLE_NO_EXIT, to avoid spurious EINTRs on resume.
Provide debugging sysctl debug.stop_all_proc, which causes total stop
and suspends syncer, while waiting for variable reset for resume. It
is used for debugging; should be removed after the real use of the
interface is added.
In collaboration with: pho
Discussed with: avg
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
This is not correct at least for the stop requests. Check for stop
conditions and suspend threads if requested.
Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
sb_cc member of struct sockbuf to a couple of inline functions:
sbavail() and sbused()
Right now they are equal, but once notion of "not ready socket buffer data",
will be checked in, they are going to be different.
Sponsored by: Netflix
Sponsored by: Nginx, Inc.
into head. The code is not believed to have any effect
on the semantics of non-NFSv4.1 server behaviour.
It is a rather large merge, but I am hoping that there will
not be any regressions for the NFS server.
MFC after: 1 month
Old design with unified thread pool was good from the point of thread
utilization. But single pool-wide mutex became huge congestion point
for systems with many CPUs. To reduce the congestion create several
thread groups within a pool (one group for every 6 CPUs and 12 threads),
each group with own mutex. Each connection during its registration is
assigned to one of the groups in round-robin fashion. File affinify
code may still move requests between the groups, but otherwise groups
are self-contained.
MFC after: 2 weeks
Sponsored by: iXsystems, Inc.
This allows to slightly simplify svc_run_internal() code: if we processed
all the requests in a queue, then we know that new one will not appear.
MFC after: 2 weeks
New algorithm does not create additional lock congestion, while some races
it includes should not be a problem. Those races may keep requests in DRC
cache for some more time by returning ACK position smaller then actual,
but it still should be able to drop thems when proper ACK finally read.
Races of the original algorithm based on TCP seq number were worse because
they happened when reply sequence number were recorded. After that even
correctly read ACKs could not clean DRC sometimes.
- Introduce additional hash to group requests by hash of sockref. This
allows to process TCP acknowledgements without looping though all the cache,
and as result allows to do it every time.
- Indroduce additional callbacks to notify application layer about sockets
disconnection. Without this last few requests processed just before socket
disconnection never processed their ACKs and stuck in cache for many hours.
- Implement transport-specific method for tracking reply acknowledgements.
New implementation does not cross multiple stack layers to get the data and
does not have race conditions that previously made some requests stuck
in cache. This could be done more efficiently at sockbuf layer, but that
would broke some KBIs, while I don't know other consumers for it aside NFS.
- Instead of traversing all DRC twice per request, run cleaning only once
per request, and except in some conditions traverse only single hash slot
at a time.
Together this limits NFS DRC growth only to situations of real connectivity
problems. If network is working well, and so all replies are acknowledged,
cache remains almost empty even after hours of heavy load. Without this
change on the same test cache was growing to many thousand requests even
with perfectly working local network.
As another result this reduces CPU time spent on the DRC handling during
SPEC NFS benchmark from about 10% to 0.5%.
Sponsored by: iXsystems, Inc.
Do not insert active ports into pool->sp_active list if they are success-
fully assigned to some thread. This makes that list include only ports that
really require attention, and so traversal can be reduced to simple taking
the first one.
Remove idle thread from pool->sp_idlethreads list when assigning some
work (port of requests) to it. That again makes possible to replace list
traversals with simple taking the first element.
When processing receive buffer, write the amount of data, expected
in present request record, into socket's so_rcv.sb_lowat to make stack
aware about our needs. When processing following upcalls, ignore them
until socket collect enough data to be read and processed in one turn.
This change reduces number of context switches and other operations
in RPC stack during large NFS writes (especially via non-Jumbo networks)
by order of magnitude.
After precessing current packet, take another look into the pending
buffer to find out whether the next packet had been already received.
If not, deactivate this port right there without making RPC code to
push this port to another thread just to find that there is nothing.
If the next packet is received partially, also deactivate the port, but
also update socket's so_rcv.sb_lowat to not be woken up prematurely.
This change additionally reduces number of context switches per NFS
request about in half.
3-clause BSD license as specified by Oracle America, Inc. in 2010.
This license change was approved by Wim Coekaerts, Senior Vice
President, Linux and Virtualization at Oracle Corporation.
- close cosmetic race in svc_exit();
- do not set wait timeout for idle threads if we have no use for wakeups;
- create new requested thread sooner, not only after some another thread
wakeup, that may happen later under constant load.
