From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f174.google.com (mail-pl1-f174.google.com [209.85.214.174]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B40FB26FA5B for ; Tue, 19 Aug 2025 12:28:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.174 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755606522; cv=none; b=hnBWUZYE30ww+kCIdMENTsjvT/TltA4z+ElRMfPt5X4QSW0CwhVkQzay9bPt2GV4C6WHrkSFZyOUmoh5X3voLwy88nWQQnYr4jhTBFZEb6FEIpCCCuafVJ2f3u0DKBRP8KDGMySqL0+2MztxiAyK2A9jFkgTT/CjruC2J8deLCU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755606522; c=relaxed/simple; bh=F930J8sPvbsU57FFnW6foQhbn/RAm3RZi0OeYZZPj6I=; h=MIME-Version:From:Date:Message-ID:Subject:To:Content-Type; b=b2PEdw2gnXOxiaSfh85sX4tF9/a+UsMQF9+HUypE2p2pfIEis75+wLpeUW5LrtCflBCrYpPjApfm3z5iipHpeuw11aNH/QN0Fot0+A/9fgg4IYZFCEeb9CQNlWMCsCjO+0B7CFMzfGs9IKRn8i83bWetQlLXGamFghbCdpVg3hg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=TIiiiak/; arc=none smtp.client-ip=209.85.214.174 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="TIiiiak/" Received: by mail-pl1-f174.google.com with SMTP id d9443c01a7336-24457f5835dso55401065ad.0 for ; Tue, 19 Aug 2025 05:28:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1755606520; x=1756211320; darn=vger.kernel.org; h=content-transfer-encoding:to:subject:message-id:date:from :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=F930J8sPvbsU57FFnW6foQhbn/RAm3RZi0OeYZZPj6I=; b=TIiiiak/D9OfoGoX5j6f+/3rmuF0y0Q9JDxU//CLyIhvIJBqid+CXxwOmCsu2FvKJ8 JChD4k9tsPEGDuPqxC6Jui5dra62QLUlXVAP37sJd+/3lmmHK7zaxuBj9c5wRHGztqqt movl5tXKtKr0ddEuY3tne2BX1Tn+58ba+QTpJo2g5K+DNqXXu5tl5dcUbdANBgSdL7Cy BnTph3h2/JD7tdzBOt5mlO5qRvzsFMWcGAjyf6OsvhYSxgaOyaD8HnLTnlW63TvzSlIA jujiXHwe/HWSD6cVR4uq/EkfHV4K6QPcmhiEYM6+H1XQxTXwxpRqy0EX15hN7FPciCbc 4RaQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1755606520; x=1756211320; h=content-transfer-encoding:to:subject:message-id:date:from :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=F930J8sPvbsU57FFnW6foQhbn/RAm3RZi0OeYZZPj6I=; b=KBWRZEzHISiaoGfv8hJZAC4r2yetgebDsKQ2hnpkGRfaTk7MTuryvPClNC81A6MMvR +p0mAlbwYx4yeor9oZJZI/scuG/eaMsn1nzEKnt/TVQzaDF9Aa7o/bI+EftHPlXNsm5O XIuOAd7et2MWmkG8PeqkJLl79OhKiSx5EKfUiusQdLmxeRKdtkm60tEbKYMl649FNBm4 IhnPFhVO9B0NVpDQrqOKep0VqjC4RQjRCmQbXj414bIWQ+AGcMkKW3yfqMto1KbCdPRJ F7PE+QNXSr0F4hl7j9V7nUxnJLFmJRcxSQdoGjKBqCBkW5Kf9Lux4eTPazymnZQCzJr1 QvGg== X-Gm-Message-State: AOJu0Yyr/1XOaQLUpLTrUAXUmZ07Iuu9wVrUITWiXuIaXl5xmSuIbzsr WFRjdvK5TNXW4B2NQ7QaP6oxEPhvODaG4DLxLTcZ2RLAYiR2kXqRIE8DsUlbg4rBaEkK0JUV85k bdQCFlf9NAEXU+X1HTg+UB94x/+LmWRuUWAXn X-Gm-Gg: ASbGncvIGxfj0L8aSPE/8xgDpgdOxY2ktJPbamaXZlVygeYAOd2xomNPGwxotuQv8p6 XVdBd1CXyJD9P5YZkLk8RkVvnFjkV9bQ+bPlEbGsmeJAhHi6yBMdxDVE4F5rTEOONOWm21ttW0s ra/GThiH3P6D8xMrkU91jm1mBeTauZTNeuqCh+P8tzAUzKZvhUf7tm2GYsplFlL6UO5BNKLiRmR 86Bfw== X-Google-Smtp-Source: AGHT+IFfVomrga1smFOqnAvQd7BfhGowk0V0w+3aGWh/pkaRsURiARTa4/o8I9tEJxDkEVNPa1SKSFoqaMwohl9Q3Cw= X-Received: by 2002:a17:903:196b:b0:240:640a:b2e4 with SMTP id d9443c01a7336-245e04df64cmr30356755ad.49.1755606519696; Tue, 19 Aug 2025 05:28:39 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-fpga@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Patryk Date: Tue, 19 Aug 2025 14:28:28 +0200 X-Gm-Features: Ac12FXxUFf5IwJnhY6zkr1gLlQeyUzEzm_ssIACtrEuY4SGgQX26OqTiAmQWXl8 Message-ID: Subject: FPGA-HPS DDR contention on Agilex5 SoC while running Linux To: linux-fpga@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hi I=E2=80=99m working on a device based on an Agilex5 SoC with HPS, which is = new hardware for me. I've been considering the following scenario: the FPGA and HPS will share DDR memory, and Linux is running on the HPS at the same time. The FPGA will be streaming a high volume of data that needs to be consumed by a userspace program on the CPU. I=E2=80=99m concerned that if the FPGA saturates the memory interconnect, t= he kernel might struggle to perform memory allocations or other transactions for other threads. Has anyone encountered this kind of bus contention on Agilex/SoC platforms? What strategies do you use to prevent FPGA traffic from starving HPS memory accesses while Linux is running? Also, is there any recommendation / strategy for an FPGA and a userspace program on Linux to exchange data efficiently and safely in this kind of setup? I don't expect in-depth answers, and will be grateful for anything that will channel me in the right direction. Best regards Patryk