Re: [PATCH v8 6/6] tcp: Clamp the retry timeout

On Fri, 14 Nov 2025 14:35:12 +1100 David Gibson wrote:

On Fri, Nov 14, 2025 at 11:05:51AM +0800, Yumei Huang wrote:

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On Fri, Nov 14, 2025 at 8:47 AM David Gibson wrote:

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On Fri, Nov 14, 2025 at 01:01:21AM +0100, Stefano Brivio wrote:

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On Mon, 10 Nov 2025 21:56:39 +1100 David Gibson wrote:

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On Mon, Nov 10, 2025 at 05:31:37PM +0800, Yumei Huang wrote:

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@@ -2811,10 +2821,15 @@ void tcp_get_rto_params(struct ctx *c) v = read_file_integer(SYN_LINEAR_TIMEOUTS, SYN_LINEAR_TIMEOUTS_DEFAULT); c->tcp.syn_linear_timeouts = MIN(v, MAX_SYNCNT);

+ v = read_file_integer(RTO_MAX_MS, RTO_MAX_MS_DEFAULT); + c->tcp.rto_max = MIN(DIV_ROUND_CLOSEST(v, 1000), INT_MAX);

Possibly we should verify this is => RTO_INIT.

As a sanity check, maybe, but I don't see any harmful effect if it's < RTO_INIT, right? So I'm not sure if we should. No preference from my side really.

Sorry, describing this as >= RTO_INIT was misleading. What I'm concerned about here is if the kernel value is set to 400ms, we'll round it to... 0s.

So, really what I'm concerned about is that we ensure this is > 0.

That's a good point.

Actually, thinking about it, I wonder if makes more sense to always round up to 1s, rather than to the nearest 1s.

I guess so, yes. Using two seconds as timeout when the user configured 1400ms isn't necessarily less correct than using one second, and it simplifies things (we already have DIV_ROUND_UP()). -- Stefano