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[34.48.4.250]) by smtp.gmail.com with UTF8SMTPSA id 956f58d0204a3-6470d8b2623sm2643462d50.20.2026.01.07.15.51.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Jan 2026 15:51:38 -0800 (PST) Date: Wed, 07 Jan 2026 18:51:38 -0500 From: Willem de Bruijn To: Jakub Kicinski , davem@davemloft.net Cc: netdev@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, andrew+netdev@lunn.ch, horms@kernel.org, Jakub Kicinski , willemb@google.com, anubhavsinggh@google.com, mohsin.bashr@gmail.com, shuah@kernel.org, linux-kselftest@vger.kernel.org Message-ID: In-Reply-To: <20260107232557.2147760-1-kuba@kernel.org> References: <20260107232557.2147760-1-kuba@kernel.org> Subject: Re: [PATCH net-next] selftests: drv-net: gro: increase the rcvbuf size Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Jakub Kicinski wrote: > The gro.py test (testing software GRO) is slightly flaky when > running against fbnic. We see one flake per roughly 20 runs in NIPA, > mostly in ipip.large, and always including some EAGAIN: > > # Shouldn't coalesce if exceed IP max pkt size: Test succeeded > # Expected {65475 899 }, Total 2 packets > # Received {65475 899 }, Total 2 packets. > # Expected {64576 900 900 }, Total 3 packets > # Received {64576 /home/virtme/testing/wt-24/tools/testing/selftests/drivers/net/gro: could not receive: Resource temporarily unavailable > > The test sends 2 large frames (64k + change). Looks like the default > packet socket rcvbuf (~200kB) may not be large enough to hold them. > Bump the rcvbuf to 1MB. > > Add a debug print showing socket statistics to make debugging this > issue easier in the future. Without the rcvbuf increase we see: > > # Shouldn't coalesce if exceed IP max pkt size: Test succeeded > # Expected {65475 899 }, Total 2 packets > # Received {65475 899 }, Total 2 packets. > # Expected {64576 900 900 }, Total 3 packets > # Received {64576 Socket stats: packets=7, drops=3 > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > # /home/virtme/testing/wt-24/tools/testing/selftests/drivers/net/gro: could not receive: Resource temporarily unavailable > > Signed-off-by: Jakub Kicinski Reviewed-by: Willem de Bruijn