Re: [PATCH V2 net 2/9] net: hns3: add sync command to sync io-pgtable

on 2024/10/24 16:36, Paolo Abeni wrote:

On 10/18/24 12:10, Jijie Shao wrote:

quoted

From: Jian Shen <shenjian15@huawei.com>

To avoid errors in pgtable prefectch, add a sync command to sync
io-pagtable.

In the case of large traffic, the TX bounce buffer may be used up.

It's unclear to me what do you mean for large traffic. Is that large
packets instead?

Skimming over the previous patch, it looks like the for the bugger H/W
driver will use the bounce buffer for all packets with len < 64K. As
this driver does not support big tcp, such condition means all packets.

So its not clear to me the 'may' part - it looks like the critical path
will always happen on the bugged H/W

Sorry, actually not, I mean with tools like iperf3, we can hit the speed limit.
In this case, many packets are sent within a short period of time.
Therefore, the TX bounce buffer may be used up.
In this case, mapping/unmapping is used for packets that cannot use the TX bounce buffer.

Thanks,
Jijie Shao

quoted

At this point, we go to mapping/unmapping on TX path again.
So we added the sync command in driver to avoid hardware issue.

I thought the goal of the previous patch was to avoid such sync-up.

So I don't understand why it's there.

A more verbose explanation will help.

quoted

Signed-off-by: Jian Shen <shenjian15@huawei.com>
Signed-off-by: Peiyang Wang <redacted>
Signed-off-by: Jijie Shao <shaojijie@huawei.com>

Also we need a fixes tag.

Thanks,

Paolo