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Chuck Lever 4a85a6a332 SUNRPC: Handle TCP socket sends with kernel_sendpage() again 
Daire Byrne reports a ~50% aggregrate throughput regression on his
Linux NFS server after commit da1661b93b ("SUNRPC: Teach server to
use xprt_sock_sendmsg for socket sends"), which replaced
kernel_send_page() calls in NFSD's socket send path with calls to
sock_sendmsg() using iov_iter.

Investigation showed that tcp_sendmsg() was not using zero-copy to
send the xdr_buf's bvec pages, but instead was relying on memcpy.
This means copying every byte of a large NFS READ payload.

It looks like TLS sockets do indeed support a ->sendpage method,
so it's really not necessary to use xprt_sock_sendmsg() to support
TLS fully on the server. A mechanical reversion of da1661b93b is
not possible at this point, but we can re-implement the server's
TCP socket sendmsg path using kernel_sendpage().

Reported-by: Daire Byrne <daire@dneg.com>
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=209439
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-12-18 12:28:41 -05:00
arch Merge branch 'parisc-5.11-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux 2020-12-16 12:10:40 -08:00
block Scheduler updates: 2020-12-14 18:29:11 -08:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto crypto: aegis128 - avoid spurious references crypto_aegis128_update_simd 2020-12-04 18:16:53 +11:00
Documentation MIPS updates for v5.11: 2020-12-16 12:07:54 -08:00
drivers MIPS updates for v5.11: 2020-12-16 12:07:54 -08:00
fs NFSD: Fix sparse warning in nfssvc.c 2020-12-18 12:28:23 -05:00
include MIPS updates for v5.11: 2020-12-16 12:07:54 -08:00
init printk changes for 5.11 2020-12-16 10:45:11 -08:00
ipc Merge branch 'akpm' (patches from Andrew) 2020-12-15 12:53:37 -08:00
kernel seccomp updates for v5.11-rc1 2020-12-16 11:30:10 -08:00
lib fallthrough fixes for Clang for 5.11-rc1 2020-12-16 00:24:16 -08:00
LICENSES LICENSES: Add the CC-BY-4.0 license 2020-12-08 10:33:27 -07:00
mm Merge branch 'parisc-5.11-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux 2020-12-16 12:10:40 -08:00
net SUNRPC: Handle TCP socket sends with kernel_sendpage() again 2020-12-18 12:28:41 -05:00
samples samples/bpf: Fix possible hang in xdpsock with multiple threads 2020-12-10 23:13:43 +01:00
scripts gcc-plugins updates for v5.11-rc1 2020-12-16 11:17:27 -08:00
security Smack updates for Linux 5.11. One minor code clean-up and a 2020-12-16 11:11:58 -08:00
sound ACPI updates for 5.11-rc1 2020-12-15 16:39:06 -08:00
tools seccomp updates for v5.11-rc1 2020-12-16 11:30:10 -08:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt kvm: x86/mmu: Support dirty logging for the TDP MMU 2020-10-23 03:42:13 -04:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: docs: ignore sphinx_*/ directories 2020-09-10 10:44:31 -06:00
.mailmap MIPS updates for v5.11: 2020-12-16 12:07:54 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-12-11 22:29:38 -08:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MIPS updates for v5.11: 2020-12-16 12:07:54 -08:00
Makefile Linux 5.10 2020-12-13 14:41:30 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

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.

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.