Add command-line argument for debugging purposes (-dm) and only print the last_size info when debug is enabled #324
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* -dm = Enable developer mode. Enables debug prints and asserts.
* This sets to true a global variable _G.developer_debug that can be
used on the rest of snabswitch to enable prints, asserts or other
things that are not intended for production.
* Make all other parts of snabswitch where a debug variable was used
(or should be used) to depend on this one.
* This code starts triggering on a kernel >= 3.14 (Ubuntu 14.04 uses
3.13, so this went unnoticed). It causes a lot of flood because it
triggers constantly.
* Example of the output from snabswitch when running same_vlan.ports
with both VMs running Kernel 3.14.23 and running an iperf test
(MTU 1500) between both VMs:
size= 2036
size= 1524
size= 2036
size= 1524
size= 2036
size= 1524
[ .... repeated ad-infinitum ]
* I have bisected the Linux kernel, the commit that causes this print to
trigger is fb51879dbceab9c40a39018d5322451691909e15 (merged on 3.14)
https://git.kernel.org/linus/fb51879
Closed
| @@ -259,7 +259,7 @@ function VirtioNetDevice:vm_buffer (iovec) | |||
| iovec.offset = 0 | |||
| end | |||
| end | |||
| if last_size ~= b.size then print("size=", b.size) last_size=b.size end | |||
| if last_size ~= b.size then debug("size=", b.size) last_size=b.size end | |||
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Can we somehow disable this whole line when debug is not enabled.
I know how to do it in C with macros, what is the right approach in Lua?
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Maybe we can do something like:
if _G.developer_debug then
if last_size ~= b.size then debug("size=", b.size) last_size=b.size end
end
?
lukego
added a commit
that referenced
this pull request
Nov 24, 2014
Add command-line argument for debugging purposes (-dm) and only print the last_size info when debug is enabled
|
Good idea, thanks for the patch! |
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The first commit on this PR adds a new command line to snabswitch:
used on the rest of snabswitch to enable prints, asserts or other
things that are not intended for production.
(or should be used) to depend on this one.
The second commit makes the last_size print check to happen only when debug is enabled (previously debug was just an alias to print). Check PR #323 for info about this issue