From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oa1-f46.google.com (mail-oa1-f46.google.com [209.85.160.46]) (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 2FBD3487B0 for ; Tue, 21 May 2024 21:59:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.46 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716328751; cv=none; b=gQwo4kn7NFkx2TRG9itfFM3ydu+9Zi5PTXI0wVH1tb8t9LydTBGEmeMxT9CgJhnLi7pm3aDtYP4J/zq9KuPuT5Ei5D3acnxSYbuJRjYKZlar5RD2spjveYeDyD9dfAP4g3w/vu410FsbH1lJJHPV+fKei2ENggOSR9F6DUi+xlo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716328751; c=relaxed/simple; bh=XaigkbOwLK+o1X5tNLLDmxiVQ6E5qgREURmagb19brs=; h=Message-ID:Date:MIME-Version:To:From:Cc:Subject:Content-Type; b=mHhbC0fF4G91dgSPyxHY1LVXU9xQL4czfNsvPLaMLhMUje1a7hp7zQt0zoSMXVve6uHcoqwVl+eGokyTBzHUINjE/F7Tltf4FgrPkH0YAZrpr+UFOAys4jO2jMITdEmgqq7rkYpfbCXmQF/Iaum7r0Q7aKVc5TbtF3WzcQsXbFg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=DvdswmPa; arc=none smtp.client-ip=209.85.160.46 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="DvdswmPa" Received: by mail-oa1-f46.google.com with SMTP id 586e51a60fabf-241ad94775eso2409076fac.1 for ; Tue, 21 May 2024 14:59:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1716328749; x=1716933549; darn=vger.kernel.org; h=content-transfer-encoding:subject:cc:content-language:from:to :user-agent:mime-version:date:message-id:from:to:cc:subject:date :message-id:reply-to; bh=MCulgS4xL8QwT0myBjRcudy93UEfdd7jkeB5GVj1pM0=; b=DvdswmPaC7SN1it7BBpUXfhCIbu260xBxmZtTPPl1aier+w3keUuSrsrb4wA9W82Rg 33tVll5y75lIH9oS8ZyTTR+9CfmvTET1kCvD2UPjf6sbUxgB2d0eOgTW8/AnUVs9EQF7 ek5Vbc/5DKtYF/3ZxlJoeg6hYvvuSmXuUGPbk8EQucNWOw9tq/YopzeIe87l+/YcCG2z GYaXNNH0Ro+lS65EMwkm3hFZ5Ld++BoTGPyFlqo93wo8AH3AU3vfoNoj6YGra5RBozzS WwrvVvP5AO5z2MVvFaiQDUKI0d56vLH3H9x+UJxGa6/W7KgrXl8QWAvQzw1tIyBBniAt S3Qg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1716328749; x=1716933549; h=content-transfer-encoding:subject:cc:content-language:from:to :user-agent:mime-version:date:message-id:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=MCulgS4xL8QwT0myBjRcudy93UEfdd7jkeB5GVj1pM0=; b=dpcRenEdhYzkI7AZKsV89Ur6ScjTnHacduJk6WwgOyw2/TIdXob6RsHtk+NXW2bvo1 ywXcZPktZFXr8UrWS2U2ujJdchydUnW1IiMBTu8oM85k0pf16kTnqg+pZOOoTVSjFpHl fm4KPNGdMcovRUhHachxSU4v76lyxVNikbynKkn7NCT75bc6loxMJ9THiT854RM3QFxz 6BtRDcLg9laJTkXgXsPeLSCoJ7Pg0yaigXknRf+qZLkrs2wvImnGynADsZCm55JmCP+X h1ivPj+oc3gk4l6u0CkLNYqU3b0bIbze7VFXvy4X2MOlglaLs1bhhDf170KgLMgiCSBn 5tlQ== X-Gm-Message-State: AOJu0Yyf+2nO2FeVGv4P6njnTa4MpXLRyPqLldOXv6FCa+znOJ8srwVk pNLdRLkYt8BMtLMNqwu/KG40aNioHOM3qYpg8g303YSu2XY1w12cUkQjI1cFORmgWNUhqXYO5qe kFA== X-Google-Smtp-Source: AGHT+IHx6jonqIFa28/KfwEWCM1lIs6KPl1kellunQcIBB5W2n5X/PcNZ83GJh7ub3R/tbF9xsB/rA== X-Received: by 2002:a05:6871:289e:b0:22e:a686:a943 with SMTP id 586e51a60fabf-24c68e06585mr375937fac.31.1716328748902; Tue, 21 May 2024 14:59:08 -0700 (PDT) Received: from [192.168.1.8] (c-73-238-17-243.hsd1.ma.comcast.net. [73.238.17.243]) by smtp.gmail.com with ESMTPSA id af79cd13be357-79312697702sm488173585a.12.2024.05.21.14.59.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 21 May 2024 14:59:08 -0700 (PDT) Message-ID: <3faf9614-d61c-47a4-b8ba-6d97ae71fd44@google.com> Date: Tue, 21 May 2024 17:59:07 -0400 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird To: bpf@vger.kernel.org From: Barret Rhoden Content-Language: en-US Cc: Dohyun Kim , Neel Natu Subject: BPF timers in hard irq context? Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit hi - we've noticed some variability in bpf timer expiration that goes away if we change the timers to run in hardirq context. i imagine the use of softirqs was to keep the potentially long-running timer callback out of hardirq, but is there anything particularly dangerous about making them run in hardirq? would you all be open to a patch that makes that a flag or something? e.g. BPF_F_TIMER_HARDIRQ. thanks, barret