From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 70FC6EEB3 for ; Fri, 7 Aug 2026 16:10:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786119004; cv=none; b=LfiO0pkKg0nb3ayOGllNw1509uQ0A4sAZnYo/+4TKofm5q+tc0ZW1PlZkFHJyS4SmoNN44M24zBCtkD01EWVKHF9v/15UMCCihK64SOqBm0qC8jxv58XSpUErk9WrGiG+GtvPQgQQTYOR1FZZszDRpu4avKwqJA82JyXFl8xP4U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786119004; c=relaxed/simple; bh=gsaSOHo3SGefqsy4hDslpLglCx5SAB23qyw0r9GJw5Q=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=HRdNJQNML0SgpJcp5mBi+7Zq3f5K6cUvuELnTLLzUhI44NYVHDp6HDHBwuQJOGIJDRzZ+VqehssE6piWv1AzC4PQhHZ0JGKWGO3Unvi06ktRgrTRxN4ERc6hNSNpI9HKkSBFjLDb6Fsakz5GTeRyUQcul7Nz/63K7QZE6BPL9q0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=U9VJDDtM; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="U9VJDDtM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 99BFD1F000E9; Fri, 7 Aug 2026 16:10:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786119003; bh=XkQF/dym1AspfXKdlLBeYze48CiBLWBPn+jVL224n1E=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=U9VJDDtM6DAbzehNwnEPXEZWKbVUuJKhW0/JArXMO2lHzcu8RTAGiAIqxGYKlBW0T ZtNX3kv9OSgIiwdLyxcaJcyh4ssR/WEkQ7JUHsPUjDmGfYusBcbuyF/TQkyzCSZ/7a pTkiJDu0qoQaUTMxq+6SlIQloS+V4ceGJuD0jc+sry6VfsRNoRQNeZweIMOqdfez9J kAX7Df6szb5KmTiJvztqB9zm3wyByiqxfZuwiW9zy6vfOY1hXEB7Jt15WGSH8VvDAM Cpbov9g6C40f1Y+tEpz06Pqa/0LzUilHRr+0JYFb8/WXMcSJDf/BPPM3HzKzjyaEpB oN4AumBJ9brzQ== Message-ID: <3240b6e2-e5d5-4356-8a8e-9374086c98ec@kernel.org> Date: Fri, 7 Aug 2026 18:10:00 +0200 Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [PATCH mptcp-next 1/3] mptcp: sched: penalise a slow subflow by halving its cwnd Content-Language: fr To: Shardul Bankar Cc: MPTCP Linux , janak@mpiric.us References: <20260726-mptcp_penalise_send-v1-0-84485e0e995b@mpiricsoftware.com> <20260726-mptcp_penalise_send-v1-1-84485e0e995b@mpiricsoftware.com> <085c3192-1adc-4016-ab27-a0c053a2f2c1@kernel.org> <087874be7587606209365cb9e9791a9f0e11b934.camel@mpiricsoftware.com> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit Hi Shardul, Thank you for your reply! On 07/08/2026 17:18, Shardul Bankar wrote: > On Wed, 2026-07-29 at 13:49 +0200, Matthieu Baerts wrote: >> On 26/07/2026 07:55, Shardul Bankar wrote: (...) >>> diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h >>> index da40c6f3705f..2bf801292563 100644 >>> --- a/net/mptcp/protocol.h >>> +++ b/net/mptcp/protocol.h >>> @@ -587,6 +587,7 @@ struct mptcp_subflow_context { >>>                 __unused : 8; >>>         bool    data_avail; >>>         bool    scheduled; >>> +       bool    penalise;           /* scheduler flagged this >>> subflow for cwnd halving */ >> >> (If you don't need to read this locklessly, then you can probably use >> one unused bit.) >> > > It is written under two locks (set in the scheduler under the msk lock, > cleared in the push path under the subflow lock), so a shared bitfield > word would race on the read-modify-write, and I kept it a bool for that > reason. If you see a single-lock way to do it, I am glad to move it to > a bit. I didn't check all entries from the bitfield a few lines above, but are they not also written under the subflow lock? (but maybe not under the msk lock) But if you saw a risk, fine to keep it like that. Cheers, Matt -- Sponsored by the NGI0 Core fund.