From: Jim Baxter <jim_baxter@mentor.com>
To: <linux-usb@vger.kernel.org>, <netdev@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, Oliver Neukum <oliver@neukum.org>
Cc: <jim_baxter@mentor.com>
Subject: [RFC V1 0/1] Reduce cdc_ncm memory use when kernel memory low
Date: Tue, 16 May 2017 18:41:19 +0100 [thread overview]
Message-ID: <1494956480-6127-1-git-send-email-jim_baxter@mentor.com> (raw)
Please review this patch
Problem
-------
We are using an ARM embedded platform and require 16KiB NTB's to allow for fast
data transfer. Unfortunately we have found that there are times after
running the kernel for a while and transferring a lot of data over the CDC-NCM
connection that it can become harder to find 16KiB pages of memory for
allocation.
This results in a disconnection of the NCM Gadget attached to the host platform.
We are running with reduced buffers to not cross over into the 32KiB page
boundary by setting the buffer sizes to:
tx_max=16000
rx_max=16000
Analysis
--------
We identified through investigation that the lack of 16KiB pages would be short
lived as the kernel would compact the buddy list soon after the failure which
results in pages being available within seconds.
Solution
--------
In order to avoid disconnections I implemented a patch that will attempt to
use a 2048 Byte minimum size NTB if the allocation of the maximum size NTB
fails.
This allows the connection to limp along until the memory has been recovered
which was usually between 1 and 4 NTBS on our heavy traffic system.
Jim Baxter (1):
net: cdc_ncm: Reduce memory use when kernel memory low
drivers/net/usb/cdc_ncm.c | 39 +++++++++++++++++++++++++++------------
include/linux/usb/cdc_ncm.h | 1 +
2 files changed, 28 insertions(+), 12 deletions(-)
--
1.9.1
next reply other threads:[~2017-05-16 17:41 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-16 17:41 Jim Baxter [this message]
2017-05-16 17:41 ` [RFC V1 1/1] net: cdc_ncm: Reduce memory use when kernel memory low Jim Baxter
2017-05-16 18:24 ` Bjørn Mork
2017-05-17 7:44 ` Oliver Neukum
2017-05-17 10:56 ` Baxter, Jim
2017-05-17 18:18 ` David Miller
2017-05-18 10:01 ` Oliver Neukum
2017-05-22 15:45 ` Baxter, Jim
2017-05-22 15:54 ` David Miller
2017-05-23 8:42 ` Oliver Neukum
2017-05-23 15:26 ` David Miller
2017-05-23 19:06 ` Baxter, Jim
[not found] ` <1497263047.15677.13.camel@suse.com>
2017-06-12 12:32 ` Baxter, Jim
2017-05-19 11:10 ` David Laight
2017-05-19 13:55 ` Bjørn Mork
2017-05-19 14:46 ` David Laight
2017-05-22 13:27 ` Oliver Neukum
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