[PATCH 0/3] small documentation updates

[PATCH 0/3] small documentation updates

[Bruce Richardson]

Small changes to the Linux GSG and the FAQ

Bruce Richardson (3):
  doc: clarify documentation on running as non-root
  doc: remove unneeded TLB from title of FAQ question 2
  doc: update FAQ with new testpmd default burst size

 doc/guides/faq/faq.rst               | 18 +++++++++---------
 doc/guides/linux_gsg/enable_func.rst |  8 ++++++++
 2 files changed, 17 insertions(+), 9 deletions(-)

-- 
2.13.3

[PATCH 1/3] doc: clarify documentation on running as non-root

[Bruce Richardson]

Since modern kernels don't allow unprivileged processes to read the
pagemaps file, the instructions on running as non-root are out-of-date. Add
a note clarifying that they will only work with earlier kernel versions.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
 doc/guides/linux_gsg/enable_func.rst | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/doc/guides/linux_gsg/enable_func.rst b/doc/guides/linux_gsg/enable_func.rst
index e6c806b0d..5ac0184a1 100644
--- a/doc/guides/linux_gsg/enable_func.rst
+++ b/doc/guides/linux_gsg/enable_func.rst
@@ -87,6 +87,14 @@ The application can then determine what action to take, if any, if the HPET is n
 Running DPDK Applications Without Root Privileges
 --------------------------------------------------------
 
+.. note::
+
+    The instructions below will allow running DPDK as non-root with older
+    Linux kernel versions. However, since version 4.0, the kernel does not allow
+    unprivileged processes to read the physical address information from
+    the pagemaps file, making it impossible for those processes to use HW
+    devices which require physical addresses
+
 Although applications using the DPDK use network ports and other hardware resources directly,
 with a number of small permission adjustments it is possible to run these applications as a user other than "root".
 To do so, the ownership, or permissions, on the following Linux file system objects should be adjusted to ensure that
-- 
2.13.3

[PATCH 2/3] doc: remove unneeded TLB from title of FAQ question 2

[Bruce Richardson]

Hugepages are just that, hugepages. The TLB is a sort of cache for doing
address translation and does not need to be referenced in the title, since
"TLB hugepages" doesn't make any sense (as there are no non-TLB hugepages
that you can allocate).

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
 doc/guides/faq/faq.rst | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/doc/guides/faq/faq.rst b/doc/guides/faq/faq.rst
index aa1d47d3f..f21aff4c5 100644
--- a/doc/guides/faq/faq.rst
+++ b/doc/guides/faq/faq.rst
@@ -37,8 +37,8 @@ Alternatively, applications can also be run as regular user.
 For more information, please refer to :ref:`DPDK Getting Started Guide <linux_gsg>`.
 
 
-If I want to change the number of TLB Hugepages allocated, how do I remove the original pages allocated?
---------------------------------------------------------------------------------------------------------
+If I want to change the number of hugepages allocated, how do I remove the original pages allocated?
+----------------------------------------------------------------------------------------------------
 
 The number of pages allocated can be seen by executing the following command::
 
-- 
2.13.3

[PATCH 3/3] doc: update FAQ with new testpmd default burst size

[Bruce Richardson]

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
 doc/guides/faq/faq.rst | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/doc/guides/faq/faq.rst b/doc/guides/faq/faq.rst
index f21aff4c5..dac805099 100644
--- a/doc/guides/faq/faq.rst
+++ b/doc/guides/faq/faq.rst
@@ -115,16 +115,16 @@ but the end-to-end latency of an average packet typically increases as a result.
 Similarly, the application can be tuned to have, on average, a low end-to-end latency at the cost of lower throughput.
 
 To achieve higher throughput, the DPDK attempts to aggregate the cost of processing each packet individually by processing packets in bursts.
-Using the testpmd application as an example, the "burst" size can be set on the command line to a value of 16 (also the default value).
-This allows the application to request 16 packets at a time from the PMD.
-The testpmd application then immediately attempts to transmit all the packets that were received, in this case, all 16 packets.
+Using the testpmd application as an example, the "burst" size can be set on the command line to a value of 32 (also the default value).
+This allows the application to request 32 packets at a time from the PMD.
+The testpmd application then immediately attempts to transmit all the packets that were received, in this case, all 32 packets.
 The packets are not transmitted until the tail pointer is updated on the corresponding TX queue of the network port.
 This behavior is desirable when tuning for high throughput because the cost of tail pointer updates to both the RX and TX queues
-can be spread across 16 packets, effectively hiding the relatively slow MMIO cost of writing to the PCIe* device.
+can be spread across 32 packets, effectively hiding the relatively slow MMIO cost of writing to the PCIe* device.
 
-However, this is not very desirable when tuning for low latency, because the first packet that was received must also wait for the other 15 packets to be received.
-It cannot be transmitted until the other 15 packets have also been processed because the NIC will not know to transmit the packets until the TX tail pointer has been updated,
-which is not done until all 16 packets have been processed for transmission.
+However, this is not very desirable when tuning for low latency, because the first packet that was received must also wait for the other 31 packets to be received.
+It cannot be transmitted until the other 31 packets have also been processed because the NIC will not know to transmit the packets until the TX tail pointer has been updated,
+which is not done until all 32 packets have been processed for transmission.
 
 To consistently achieve low latency even under heavy system load, the application developer should avoid processing packets in bunches.
 The testpmd application can be configured from the command line to use a burst value of 1.
-- 
2.13.3

Re: [PATCH 1/3] doc: clarify documentation on running as non-root

[Mcnamara, John]

> -----Original Message-----
> From: Richardson, Bruce
> Sent: Friday, August 4, 2017 1:44 PM
> To: Mcnamara, John <john.mcnamara@intel.com>
> Cc: dev@dpdk.org; Richardson, Bruce <bruce.richardson@intel.com>
> Subject: [PATCH 1/3] doc: clarify documentation on running as non-root
> 
> Since modern kernels don't allow unprivileged processes to read the
> pagemaps file, the instructions on running as non-root are out-of-date.
> Add a note clarifying that they will only work with earlier kernel
> versions.
> 
> Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>


Acked-by: John McNamara <john.mcnamara@intel.com>

Re: [PATCH 2/3] doc: remove unneeded TLB from title of FAQ question 2

[Mcnamara, John]

> -----Original Message-----
> From: Richardson, Bruce
> Sent: Friday, August 4, 2017 1:44 PM
> To: Mcnamara, John <john.mcnamara@intel.com>
> Cc: dev@dpdk.org; Richardson, Bruce <bruce.richardson@intel.com>
> Subject: [PATCH 2/3] doc: remove unneeded TLB from title of FAQ question 2
> 
> Hugepages are just that, hugepages. The TLB is a sort of cache for doing
> address translation and does not need to be referenced in the title, since
> "TLB hugepages" doesn't make any sense (as there are no non-TLB hugepages
> that you can allocate).
> 
> Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>

Acked-by: John McNamara <john.mcnamara@intel.com>

Re: [PATCH 2/3] doc: remove unneeded TLB from title of FAQ question 2

[Mcnamara, John]

> -----Original Message-----
> From: Richardson, Bruce
> Sent: Friday, August 4, 2017 1:44 PM
> To: Mcnamara, John <john.mcnamara@intel.com>
> Cc: dev@dpdk.org; Richardson, Bruce <bruce.richardson@intel.com>
> Subject: [PATCH 2/3] doc: remove unneeded TLB from title of FAQ question 2
> 
> Hugepages are just that, hugepages. The TLB is a sort of cache for doing
> address translation and does not need to be referenced in the title, since
> "TLB hugepages" doesn't make any sense (as there are no non-TLB hugepages
> that you can allocate).
> 
> Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>

Acked-by: John McNamara <john.mcnamara@intel.com>

Re: [PATCH 3/3] doc: update FAQ with new testpmd default burst size

[Mcnamara, John]

> -----Original Message-----
> From: Richardson, Bruce
> Sent: Friday, August 4, 2017 1:44 PM
> To: Mcnamara, John <john.mcnamara@intel.com>
> Cc: dev@dpdk.org; Richardson, Bruce <bruce.richardson@intel.com>
> Subject: [PATCH 3/3] doc: update FAQ with new testpmd default burst size
> 
> Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>

Acked-by: John McNamara <john.mcnamara@intel.com>

Re: [PATCH 3/3] doc: update FAQ with new testpmd default burst size

[Thomas Monjalon]

> > Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> 
> Acked-by: John McNamara <john.mcnamara@intel.com>

Fixes: 836853d3d4cf ("app/testpmd: increase default burst size to 32")

Re: [PATCH 0/3] small documentation updates

[Thomas Monjalon]

> Bruce Richardson (3):
>   doc: clarify documentation on running as non-root
>   doc: remove unneeded TLB from title of FAQ question 2
>   doc: update FAQ with new testpmd default burst size

Applied, thanks