[dpdk-dev] [PATCH] doc/nic: add ixgbe statistics on read frequency

[dpdk-dev] [PATCH] doc/nic: add ixgbe statistics on read frequency

[Harry van Haaren]

This patch adds a note to the ixgbe PMD guide, stating
the minimum time that statistics must be polled from
the hardware in order to avoid register values becoming
saturated and "sticking" to the max value.

Signed-off-by: Harry van Haaren <harry.van.haaren@intel.com>
---
 doc/guides/nics/ixgbe.rst | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/doc/guides/nics/ixgbe.rst b/doc/guides/nics/ixgbe.rst
index 8cae299..c8085a8 100644
--- a/doc/guides/nics/ixgbe.rst
+++ b/doc/guides/nics/ixgbe.rst
@@ -178,3 +178,27 @@ load_balancer
 
 As in the case of l3fwd, set configure port_conf.rxmode.hw_ip_checksum=0 to enable vPMD.
 In addition, for improved performance, use -bsz "(32,32),(64,64),(32,32)" in load_balancer to avoid using the default burst size of 144.
+
+Statistics
+----------
+
+The statistics of ixgbe hardware must be polled regularly in order for it to
+remain consistent. Running a DPDK application without polling the statistcs will
+cause registers on hardware to count to thier maxiumum value, and "stick" at
+that value.
+
+In order to avoid statistic registers every reaching thier maxiumum value,
+read the statistics from the hardware using ``rte_eth_stats_get()`` or
+``rte_eth_xstats_get()``.
+
+The maxiumum time between statistics polls that ensures consistent results can
+be calculated as follows:
+
+.. code-block:: c
+
+  max_read_interval = UINT_MAX / max_packets_per_second
+  max_read_interval = 4294967295 / 14880952
+  max_read_interval = 288.6218096127183 (seconds)
+  max_read_interval = ~4 mins 48 sec.
+
+In order to ensure valid results, it is recommended to poll every 4 minutes.
-- 
2.5.0

[dpdk-dev] [PATCH v2] doc/nic: add ixgbe statistics on read frequency

[Harry van Haaren]

This patch adds a note to the ixgbe PMD guide, stating
the minimum time that statistics must be polled from
the hardware in order to avoid register values becoming
saturated and "sticking" to the max value.

Reported-by: Jerry Zhang <jerry.zhang@intel.com>
Tested-by: Marcin Kerlin <marcinx.kerlin@intel.com>
Signed-off-by: Harry van Haaren <harry.van.haaren@intel.com>
---

v2: Add reported-by and tested-by

 doc/guides/nics/ixgbe.rst | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/doc/guides/nics/ixgbe.rst b/doc/guides/nics/ixgbe.rst
index 8cae299..c8085a8 100644
--- a/doc/guides/nics/ixgbe.rst
+++ b/doc/guides/nics/ixgbe.rst
@@ -178,3 +178,27 @@ load_balancer
 
 As in the case of l3fwd, set configure port_conf.rxmode.hw_ip_checksum=0 to enable vPMD.
 In addition, for improved performance, use -bsz "(32,32),(64,64),(32,32)" in load_balancer to avoid using the default burst size of 144.
+
+Statistics
+----------
+
+The statistics of ixgbe hardware must be polled regularly in order for it to
+remain consistent. Running a DPDK application without polling the statistcs will
+cause registers on hardware to count to thier maxiumum value, and "stick" at
+that value.
+
+In order to avoid statistic registers every reaching thier maxiumum value,
+read the statistics from the hardware using ``rte_eth_stats_get()`` or
+``rte_eth_xstats_get()``.
+
+The maxiumum time between statistics polls that ensures consistent results can
+be calculated as follows:
+
+.. code-block:: c
+
+  max_read_interval = UINT_MAX / max_packets_per_second
+  max_read_interval = 4294967295 / 14880952
+  max_read_interval = 288.6218096127183 (seconds)
+  max_read_interval = ~4 mins 48 sec.
+
+In order to ensure valid results, it is recommended to poll every 4 minutes.
-- 
2.5.0

Re: [dpdk-dev] [PATCH v2] doc/nic: add ixgbe statistics on read frequency

[Kerlin, MarcinX]

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Harry van Haaren
> Sent: Monday, February 29, 2016 1:17 PM
> To: Mcnamara, John <john.mcnamara@intel.com>
> Cc: dev@dpdk.org
> Subject: [dpdk-dev] [PATCH v2] doc/nic: add ixgbe statistics on read
> frequency
> 
> This patch adds a note to the ixgbe PMD guide, stating the minimum time
> that statistics must be polled from the hardware in order to avoid register
> values becoming saturated and "sticking" to the max value.
> 
> Reported-by: Jerry Zhang <jerry.zhang@intel.com>
> Tested-by: Marcin Kerlin <marcinx.kerlin@intel.com>
> Signed-off-by: Harry van Haaren <harry.van.haaren@intel.com>

Acked-by: Marcin Kerlin <marcinx.kerlin@intel.com>

Re: [dpdk-dev] [PATCH v2] doc/nic: add ixgbe statistics on read frequency

[Thomas Monjalon]

2016-02-29 12:17, Harry van Haaren:
> +cause registers on hardware to count to thier maxiumum value, and "stick" at

typos: thier maxiumum
There are other occurences below. I suggest a spell checker :)

[dpdk-dev] [PATCH v3] doc/nic: add ixgbe statistics on read frequency

[Harry van Haaren]

This patch adds a note to the ixgbe PMD guide, stating
the minimum time that statistics must be polled from
the hardware in order to avoid register values becoming
saturated and "sticking" to the max value.

Reported-by: Jerry Zhang <jerry.zhang@intel.com>
Tested-by: Marcin Kerlin <marcinx.kerlin@intel.com>
Signed-off-by: Harry van Haaren <harry.van.haaren@intel.com>
Acked-by: Marcin Kerlin <marcinx.kerlin@intel.com>
---

v3:
- Run spell checker

v2:
- Add reported and tested by tags

 doc/guides/nics/ixgbe.rst | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/doc/guides/nics/ixgbe.rst b/doc/guides/nics/ixgbe.rst
index 0ee4ebc..a00c3b4 100644
--- a/doc/guides/nics/ixgbe.rst
+++ b/doc/guides/nics/ixgbe.rst
@@ -199,3 +199,28 @@ When using kernel PF + DPDK VF on x550, please make sure using the kernel
 driver that disables MDD or can disable MDD. (Some kernel driver can use
 this CLI 'insmod ixgbe.ko MDD=0,0' to disable MDD. Some kernel driver disables
 it by default.)
+
+
+Statistics
+----------
+
+The statistics of ixgbe hardware must be polled regularly in order for it to
+remain consistent. Running a DPDK application without polling the statistics will
+cause registers on hardware to count to the maximum value, and "stick" at
+that value.
+
+In order to avoid statistic registers every reaching the maximum value,
+read the statistics from the hardware using ``rte_eth_stats_get()`` or
+``rte_eth_xstats_get()``.
+
+The maximum time between statistics polls that ensures consistent results can
+be calculated as follows:
+
+.. code-block:: c
+
+  max_read_interval = UINT_MAX / max_packets_per_second
+  max_read_interval = 4294967295 / 14880952
+  max_read_interval = 288.6218096127183 (seconds)
+  max_read_interval = ~4 mins 48 sec.
+
+In order to ensure valid results, it is recommended to poll every 4 minutes.
-- 
2.5.0

Re: [dpdk-dev] [PATCH v3] doc/nic: add ixgbe statistics on read frequency

[Thomas Monjalon]

2016-03-08 14:29, Harry van Haaren:
> This patch adds a note to the ixgbe PMD guide, stating
> the minimum time that statistics must be polled from
> the hardware in order to avoid register values becoming
> saturated and "sticking" to the max value.
> 
> Reported-by: Jerry Zhang <jerry.zhang@intel.com>
> Tested-by: Marcin Kerlin <marcinx.kerlin@intel.com>
> Signed-off-by: Harry van Haaren <harry.van.haaren@intel.com>
> Acked-by: Marcin Kerlin <marcinx.kerlin@intel.com>

Applied, thanks