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Sunil Muthuswamy 14a1eaa882 hv_sock: perf: loop in send() to maximize bandwidth
Currently, the hv_sock send() iterates once over the buffer, puts data into
the VMBUS channel and returns. It doesn't maximize on the case when there
is a simultaneous reader draining data from the channel. In such a case,
the send() can maximize the bandwidth (and consequently minimize the cpu
cycles) by iterating until the channel is found to be full.

Perf data:
Total Data Transfer: 10GB/iteration
Single threaded reader/writer, Linux hvsocket writer with Windows hvsocket
reader
Packet size: 64KB
CPU sys time was captured using the 'time' command for the writer to send
10GB of data.
'Send Buffer Loop' is with the patch applied.
The values below are over 10 iterations.

|--------------------------------------------------------|
|        |        Current        |   Send Buffer Loop    |
|--------------------------------------------------------|
|        | Throughput | CPU sys  | Throughput | CPU sys  |
|        | (MB/s)     | time (s) | (MB/s)     | time (s) |
|--------------------------------------------------------|
| Min    |     407    |   7.048  |    401     |  5.958   |
|--------------------------------------------------------|
| Max    |     455    |   7.563  |    542     |  6.993   |
|--------------------------------------------------------|
| Avg    |     440    |   7.411  |    451     |  6.639   |
|--------------------------------------------------------|
| Median |     446    |   7.417  |    447     |  6.761   |
|--------------------------------------------------------|

Observation:
1. The avg throughput doesn't really change much with this change for this
scenario. This is most probably because the bottleneck on throughput is
somewhere else.
2. The average system (or kernel) cpu time goes down by 10%+ with this
change, for the same amount of data transfer.

Signed-off-by: Sunil Muthuswamy <sunilmut@microsoft.com>
Reviewed-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-05-22 18:00:36 -07:00
arch First round of arm64 fixes for -rc2 2019-05-22 08:36:16 -07:00
block for-5.2/block-post-20190516 2019-05-16 19:08:15 -07:00
certs kexec, KEYS: Make use of platform keyring for signature verify 2019-02-04 17:34:07 -05:00
crypto SPDX update for 5.2-rc2, round 1 2019-05-21 12:33:38 -07:00
Documentation dt-bindings: phy: dp83867: Add documentation for disabling clock output 2019-05-22 17:40:17 -07:00
drivers net: phy: Make phy_basic_t1_features use base100t1. 2019-05-22 17:46:28 -07:00
fs Fix a gfs2 sign extension bug introduced in v4.3. 2019-05-22 08:31:09 -07:00
include ipv4/igmp: shrink struct ip_sf_list 2019-05-22 17:57:37 -07:00
init treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
ipc ipc: do cyclic id allocation for the ipc object. 2019-05-14 19:52:52 -07:00
kernel SPDX update for 5.2-rc2, round 1 2019-05-21 12:33:38 -07:00
lib SPDX update for 5.2-rc2, round 1 2019-05-21 12:33:38 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
net hv_sock: perf: loop in send() to maximize bandwidth 2019-05-22 18:00:36 -07:00
samples treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 13 2019-05-21 11:28:45 +02:00
scripts SPDX update for 5.2-rc2, round 1 2019-05-21 12:33:38 -07:00
security selinux/stable-5.2 PR 20190521 2019-05-21 12:51:20 -07:00
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tools selftests: pmtu: Simplify cleanup and namespace names 2019-05-22 17:50:24 -07:00
usr user/Makefile: Fix typo and capitalization in comment section 2018-12-11 00:18:03 +09:00
virt treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
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CREDITS Char/Misc driver patches for 5.1-rc1 2019-03-06 14:18:59 -08:00
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MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-05-20 08:21:07 -07:00
Makefile Linux 5.2-rc1 2019-05-19 15:47:09 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -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.

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.