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David Howells d0b35a4203 rxrpc: Transmit more ACKs during data reception
Immediately flush any outstanding ACK on entry to rxrpc_recvmsg_data() -
which transfers data to the target buffers - if we previously had an Rx
underrun (ie. we returned -EAGAIN because we ran out of received data).
This lets the server know what we've managed to receive something.

Also flush any outstanding ACK after calling the function if it hit -EAGAIN
to let the server know we processed some data.

It might be better to send more ACKs, possibly on a time-based scheme, but
that needs some more consideration.

With this and some additional AFS patches, it is possible to get large
unencrypted O_DIRECT reads to be almost as fast as NFS over TCP.  It looks
like it might be theoretically possible to improve performance yet more for
a server running a single operation as investigation of packet timestamps
indicates that the server keeps stalling.

The issue appears to be that rxrpc runs in to trouble with ACK packets
getting batched together (up to ~32 at a time) somewhere between the IP
transmit queue on the client and the ethernet receive queue on the server.

However, this case isn't too much of a worry as even a lightly loaded
server should be receiving sufficient packet flux to flush the ACK packets
to the UDP socket.

Signed-off-by: David Howells <dhowells@redhat.com>
2018-08-01 13:28:24 +01:00
arch Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net 2018-07-24 19:21:58 -07:00
block for-linus-20180713 2018-07-14 12:28:00 -07:00
certs certs/blacklist: fix const confusion 2018-06-26 09:43:03 -07:00
crypto net: simplify sock_poll_wait 2018-07-30 09:10:25 -07:00
Documentation dt-bindings: can: xilinx_can: add Xilinx CAN FD bindings 2018-07-27 10:40:17 +02:00
drivers virtio-net: get rid of unnecessary container of rq stats 2018-07-31 10:02:01 -07:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs sysfs: Fix regression when adding a file to an existing group 2018-07-29 13:11:28 -07:00
include rxrpc: Trace socket notification 2018-08-01 13:28:23 +01:00
init Kbuild fixes for v4.18 2018-06-30 13:05:30 -07:00
ipc rhashtable: split rhashtable.h 2018-06-22 13:43:27 +09:00
kernel Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net 2018-07-24 19:21:58 -07:00
lib Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net 2018-07-24 19:21:58 -07:00
LICENSES LICENSES: Add Linux-OpenIB license text 2018-04-27 16:41:53 -06:00
mm mm: make vm_area_alloc() initialize core fields 2018-07-21 15:24:03 -07:00
net rxrpc: Transmit more ACKs during data reception 2018-08-01 13:28:24 +01:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2018-07-20 23:58:30 -07:00
scripts Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-07-18 19:32:54 -07:00
security net: sched: introduce chain object to uapi 2018-07-23 20:44:12 -07:00
sound ALSA: hda/realtek - Yet another Clevo P950 quirk entry 2018-07-18 12:17:46 +02:00
tools selftests: forwarding: Test mirror-to-gretap w/ UL team LACP 2018-07-30 09:47:21 -07:00
usr kbuild: rename built-in.o to built-in.a 2018-03-26 02:01:19 +09:00
virt Miscellaneous bugfixes, plus a small patchlet related to Spectre v2. 2018-07-18 11:08:44 -07:00
.clang-format clang-format: add configuration file 2018-04-11 10:28:35 -07:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap Merge branch 'asoc-4.17' into asoc-4.18 for compress dependencies 2018-04-26 12:24:28 +01:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS/CREDITS: Drop METAG ARCHITECTURE 2018-03-05 16:34:24 +00:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: add basic helper macros to scripts/Kconfig.include 2018-05-29 03:31:19 +09:00
MAINTAINERS Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net 2018-07-24 19:21:58 -07:00
Makefile Linux 4.18-rc6 2018-07-22 14:12:20 -07:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.