On Thu, Feb 13, 2025 at 11:16:50PM +0100, Stefano Brivio wrote:I added this a long long time ago because it dramatically improved throughput back then: with rmem_max and wmem_max >= 4 MiB, we would force send and receive buffer sizes for TCP sockets to the maximum allowed value. This effectively disables TCP auto-tuning, which would otherwise allow us to exceed those limits, as crazy as it might sound. But in any case, it made sense. Now that we have zero (internal) copies on every path, plus vhost-user support, it turns out that these settings are entirely obsolete. I get substantially the same throughput in every test we perform, even with very short durations (one second). The settings are not just useless: they actually cause us quite some trouble on guest state migration, because they lead to huge queues that need to be moved as well. Drop those settings. Signed-off-by: Stefano Brivio <sbrivio(a)redhat.com>Hooray! Reviewed-by: David Gibson <david(a)gibson.dropbear.id.au> -- David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson