From: Qi Zhang <qi.z.zhang@intel.com>
To: john.mcnamara@intel.com
Cc: dev@dpdk.org, Qi Zhang <qi.z.zhang@intel.com>
Subject: [dpdk-dev] [PATCH] doc: correct the hugepage limitation of 32 bit
Date: Thu, 27 Apr 2017 23:49:39 -0400 [thread overview]
Message-ID: <20170428034939.73090-1-qi.z.zhang@intel.com> (raw)
The hugepage memory limitation of 32 bit application is
"1GB size" but not "1GB per page size".
Signed-off-by: Qi Zhang <qi.z.zhang@intel.com>
---
doc/guides/faq/faq.rst | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/doc/guides/faq/faq.rst b/doc/guides/faq/faq.rst
index 40c793c..308a287 100644
--- a/doc/guides/faq/faq.rst
+++ b/doc/guides/faq/faq.rst
@@ -66,14 +66,14 @@ To request memory to be reserved on a specific socket, please use the --socket-m
I am running a 32-bit DPDK application on a NUMA system, and sometimes the application initializes fine but cannot allocate memory. Why is that happening?
----------------------------------------------------------------------------------------------------------------------------------------------------------
-32-bit applications have limitations in terms of how much virtual memory is available, hence the number of hugepages they are able to allocate is also limited (1 GB per page size).
-If your system has a lot (>1 GB per page size) of hugepage memory, not all of it will be allocated.
+32-bit applications have limitations in terms of how much virtual memory is available, hence the number of hugepages they are able to allocate is also limited (1 GB size).
+If your system has a lot (>1 GB size) of hugepage memory, not all of it will be allocated.
Due to hugepages typically being allocated on a local NUMA node, the hugepages allocation the application gets during the initialization depends on which
NUMA node it is running on (the EAL does not affinitize cores until much later in the initialization process).
Sometimes, the Linux OS runs the DPDK application on a core that is located on a different NUMA node from DPDK master core and
therefore all the hugepages are allocated on the wrong socket.
-To avoid this scenario, either lower the amount of hugepage memory available to 1 GB per page size (or less), or run the application with taskset
+To avoid this scenario, either lower the amount of hugepage memory available to 1 GB size (or less), or run the application with taskset
affinitizing the application to a would-be master core.
For example, if your EAL coremask is 0xff0, the master core will usually be the first core in the coremask (0x10); this is what you have to supply to taskset::
--
2.9.3
next reply other threads:[~2017-04-28 2:59 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-28 3:49 Qi Zhang [this message]
2017-04-28 7:40 ` Mcnamara, John
2017-04-30 22:24 ` Thomas Monjalon
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