[PATCH] doc: add limitation in using segment-sz in crypto-perf

[Akhil Goyal <gakhil@marvell.com>]

When segment-sz is given as parameter,
use buffer-sz in descending order.
The reason is, same scatter gather buffer list is being used
for all packet sizes which is initialized once in the beginning.
Now if a small packet case is run first,
mbuf SG list will be trimmed to a smaller number of SG and
rest of the SGs are lost resulting in segfault.
Buffers cannot be re-initialized as that will come in datapath and
will be costly.
So to workaround this, if segment-sz is passed as argument,
use values in buffer-sz in descending order.

Signed-off-by: Akhil Goyal <gakhil@marvell.com>
---
 doc/guides/tools/cryptoperf.rst | 1 +
 1 file changed, 1 insertion(+)

diff --git a/doc/guides/tools/cryptoperf.rst b/doc/guides/tools/cryptoperf.rst
index e53e2d0ebf..a3d35f6a50 100644
--- a/doc/guides/tools/cryptoperf.rst
+++ b/doc/guides/tools/cryptoperf.rst
@@ -139,6 +139,7 @@ The following are the application command-line options:
 * ``--segment-sz <n>``
 
         Set the size of the segment to use, for Scatter Gather List testing.
+        Use list of values in buffer-sz in descending order if segment-sz is used.
         By default, it is set to the size of the maximum buffer size, including the digest size,
         so a single segment is created.
 
-- 
2.25.1