On Wed, Jun 23, 2021 at 01:55:15PM +0900, Benjamin Poirier wrote:

On 2021-06-22 19:36 +0800, Coiby Xu wrote:

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On Mon, Jun 21, 2021 at 05:10:27PM +0300, Dan Carpenter wrote:

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On Mon, Jun 21, 2021 at 09:48:44PM +0800, Coiby Xu wrote:

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Commit 7c734359d3504c869132166d159c7f0649f0ab34 ("qlge: Size RX buffers
based on MTU") introduced page_chunk structure. We should add
qdev->lbq_buf_size to skb->truesize after __skb_fill_page_desc.

Add a Fixes tag.

I will fix it in next version, thanks!

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The runtime impact of this is just that ethtool will report things
incorrectly, right?  It's not 100% from the commit message.  Could you
please edit the commit message so that an ignoramous like myself can
understand it?

truesize is used in socket memory accounting, the stuff behind sysctl
net.core.rmem_max, SO_RCVBUF, ss -m, ...

Some helpful chap wrote a page about it a while ago:
http://vger.kernel.org/~davem/skb_sk.html

Thanks for the explanation and the reference!

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I'm not sure how it would affect ethtool. But according to "git log
--grep=truesize", it affects coalescing SKBs. Btw, I fixed the issue
according to the definition of truesize which according to Linux Kernel
Network by Rami Rosen, it's defined as follows,

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The total memory allocated for the SKB (including the SKB structure
itself and the size of the allocated data block).

I'll edit the commit message to include it, thanks!

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Why is this an RFC instead of just a normal patch which we can apply?

After doing the tests mentioned in the cover letter, I found Red Hat's
network QE team has quite a rigorous test suite. But I needed to return the
machine before having the time to learn about the test suite and run it by
myself. So I mark it as an RFC before I borrow the machine again to run the
test suite.

Interesting. Is this test suite based on a public project?

The test suite is written for Beaker [1] but it seems it's not public.

[1] https://fedoraproject.org/wiki/QA/Beaker

-- 
Best regards,
Coiby