From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7550F21C9FF; Tue, 17 Jun 2025 10:54:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750157699; cv=none; b=sQAbnLY8ziP47BDWVo/8hpFF2sz6wvL3XGDRnGpkPN3Pg8k1IG+O0C0bLb2/9budp0fdumA3csxjQOKj0xhV+Zot9OiQZfyj3woUwQLNS27TtUSBKiM3GfKbWUiYG8RXgOFlgsFQFYjeLCzIgxpHph7sQLIvuU1LQjXP3XcSPPo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750157699; c=relaxed/simple; bh=x3JRQH8niRtAFZyeQUyetaHm46/MXx+Fttu75P73mkQ=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=Gymap9piT3yaa1iQ0z5wk0aqdJfROz6m5447+62uKKaQikS1f60bodmftgwZ84rWqHV9iUx1uR3yV25arWO/1uMQGvzD/STEywO0fJGjeMwrLyhiLY8hOJd1e+Q6s6ASQqiAIy/nOGAzSpmRbPzbQmX2Q3dmc7264sIvigoeBck= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=eBUhnSz1; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=iFe6w24G; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="eBUhnSz1"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="iFe6w24G" From: Kurt Kanzenbach DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1750157695; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=x3JRQH8niRtAFZyeQUyetaHm46/MXx+Fttu75P73mkQ=; b=eBUhnSz1A1tVqLrAOT/WARW2n885Lw/tG3tdwYIAEe3SsGHKaS7fHwCPWW/ICf3GUfHk0R SLKrbHQUitLfGt1mQmCPhDcowQbassMjf+IBdCPAk4sDiWkUEtqG2mUyuP+w2+zaeL29Jm Iv7kzOjKETEc2Ka5WVX9U26HUyE1FMJYhDAi1ZkC4HpBxVz/dl65JzYVxcrt+2uAMKM7pz YbNVIRLvrAdSGJmu4zliN50NqU7jXXaBd7SE2o2/bvFlTjuKURAx/a+qXBqqbZh+oKFVyx G5YkYCMlmJDzowKqw87lUKBby/IfqG7uSiadTRnj7nICsQ2TYrYeR9gdE5fS9g== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1750157695; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=x3JRQH8niRtAFZyeQUyetaHm46/MXx+Fttu75P73mkQ=; b=iFe6w24GtplauDSfHxnh+rUFXKSO0nj6s0ef4xpiNqm6gbgiiUNbrc9oByMjHT4bq2BFMc QsGftWU8StJud8CA== To: Sebastian Andrzej Siewior , Marc =?utf-8?Q?Str?= =?utf-8?Q?=C3=A4mke?= Cc: linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org Subject: Re: Latency spikes on V6.15.1 Preempt RT and maybe related to intel? IGB In-Reply-To: <20250617101507.jU00mupE@linutronix.de> References: <20250613145434.T2x2ML8_@linutronix.de> <20250613195838.0-gZ6bqS@linutronix.de> <97638b0b-cd96-40e2-9dc2-5e6f767b90a4@eltropuls.de> <20250617092814.vqKdu23w@linutronix.de> <20250617100013.1o5lsPLq@linutronix.de> <20250617101507.jU00mupE@linutronix.de> Date: Tue, 17 Jun 2025 12:54:53 +0200 Message-ID: <87v7ou7i4i.fsf@jax.kurt.home> Precedence: bulk X-Mailing-List: linux-rt-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha512; protocol="application/pgp-signature" --=-=-= Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On Tue Jun 17 2025, Sebastian Andrzej Siewior wrote: > On 2025-06-17 12:03:31 [+0200], Marc Str=C3=A4mke wrote: >> Anyway: Thanks for your help Sebastian! I can probably live well with th= ese >> spikes in latency. I was more concerned that there is a deeper issue wit= h my >> config and the response time could be unbounded. > > You don't have to live with it. You could add a read after the writes in > the loop (wrfl()). This should help. Something like this, which was done for Intel e1000? https://lore.kernel.org/intel-wired-lan/20241219192743.4499-1-gerhard@engle= der-embedded.com/ Thanks, Kurt --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQJHBAEBCgAxFiEEvLm/ssjDfdPf21mSwZPR8qpGc4IFAmhRSX0THGt1cnRAbGlu dXRyb25peC5kZQAKCRDBk9HyqkZzgvMPEACWgIzrHO4Cph0hIe7lPJdWBqZJ9xVO qeZa/IcH4J/HexhqRwutvevUK3z8PHNE9I9+CtxzsuLBpbTIJkw9yD28/EmskpkW bIwolohpUHrmkqGD28sH5eB/g287SNOFAyQ+HmavjW6Qv5890j/xXKFziz80EtoU f6pzyuayc+Up7fCwRhPt7beWwZ4YJ2JMSaVMiFtrdXpgiaeB2FJNBkXWiQtu8dRd U9aiOoBnP8OnTz9HZMtloKlEf+JUVSNfo8Det/6f1TEs2Tbmp/BbN3RpjPdsBTeU 5xyqQWnSB9P+WHsU7hEonU26Wky1LYjzdTQOHmOnmv3a89p2aebncZ5CR38LmggA UrJ2QyYU2zUPjx76qnh6LqDRF/w3vab/FHgnEu4VO62dIm2K++C+KTwpqT3nIVkn dhZ05bXKOtGo5tUzIUzFnyhzxqeec/B6/qPRDIDV3CwUB0EtU01ilx1a0DtvDqqW HiCWT36TPP8TPcl6j9IZqpG+LtkmN91rwnAZvi1oO4VYl2SJy7Z+MAsFkAfBkRjI dYPPS3SGv/UXUeepx2o588tSKSx/VdhhyX5zuSQnMZLCw0QpDM1KSjhuknxCPE+U pNIIZA4FDFhWWfJcosa315IvhrcSHBoQYnjfHgGrIyQQoOQRQlWN4lYSPdDAIfeg T+wYDtIb2qc5VQ== =CsxQ -----END PGP SIGNATURE----- --=-=-=--