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Sun, 04 May 2025 23:36:31 -0700 (PDT) Received: from localhost ([1.146.78.151]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-30a3474896dsm10758374a91.19.2025.05.04.23.36.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 04 May 2025 23:36:30 -0700 (PDT) Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Mon, 05 May 2025 16:36:23 +1000 Message-Id: To: "Akihiko Odaki" Cc: , "Dmitry Fleytman" , "Jason Wang" , "Sriram Yagnaraman" , "Fabiano Rosas" , "Laurent Vivier" , "Paolo Bonzini" Subject: Re: [PATCH v3 02/12] net/e1000e: Permit disabling interrupt throttling From: "Nicholas Piggin" X-Mailer: aerc 0.19.0 References: <20250502031705.100768-1-npiggin@gmail.com> <20250502031705.100768-3-npiggin@gmail.com> In-Reply-To: Received-SPF: pass client-ip=2607:f8b0:4864:20::102d; envelope-from=npiggin@gmail.com; helo=mail-pj1-x102d.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Mon May 5, 2025 at 3:41 PM AEST, Akihiko Odaki wrote: > On 2025/05/02 12:16, Nicholas Piggin wrote: >> The spec explicitly permits xITR register interval field to have a value >> of zero to disable throttling. The e1000e model already allows for this >> in the throttling logic, so remove the minimum value for the register. >>=20 >> The spec appears to say there is a maximum observable interrupt rate >> when throttling is enabled, regardless of ITR value, so throttle timer >> calculation is clamped to that minimum value. >>=20 >> EITR registers default to 0, as specified in spec 7.4.4. >>=20 >> Signed-off-by: Nicholas Piggin >> --- >> hw/net/e1000e_core.c | 25 +++++++++++++++++-------- >> 1 file changed, 17 insertions(+), 8 deletions(-) >>=20 >> diff --git a/hw/net/e1000e_core.c b/hw/net/e1000e_core.c >> index 24138587905..96f74f1ea14 100644 >> --- a/hw/net/e1000e_core.c >> +++ b/hw/net/e1000e_core.c >> @@ -51,8 +51,17 @@ >> =20 >> #include "trace.h" >> =20 >> -/* No more then 7813 interrupts per second according to spec 10.2.4.2 *= / >> -#define E1000E_MIN_XITR (500) >> +/* >> + * A suggested range for ITR is 651-5580, according to spec 10.2.4.2, b= ut >> + * QEMU has traditionally set 500 here. >> + */ >> +#define E1000E_DEFAULT_ITR (500) > > The cover letter says this version changes "initial ITR as well as EITR"= =20 > but the ITR value is unchanged here. Forgot to commit the change? Hmm yes I must have, thanks good catch. Thanks, Nick