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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Sridhar Samudrala <sri@us.ibm.com>
Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [RFC][PATCH 3/3] TCP/IP Critical socket communication mechanism
Date: Wed, 14 Dec 2005 11:17:19 +0000	[thread overview]
Message-ID: <1134559039.25663.12.camel@localhost.localdomain> (raw)
In-Reply-To: <Pine.LNX.4.58.0512140052470.31720@w-sridhar.beaverton.ibm.com>

On Mer, 2005-12-14 at 01:12 -0800, Sridhar Samudrala wrote:
> Pass __GFP_CRITICAL flag with all allocation requests that are critical.
> - All allocations needed to process incoming packets are marked as CRITICAL.
>   This includes the allocations
>      - made by the driver to receive incoming packets
>      - to process and send ARP packets
>      - to create new routes for incoming packets

But your user space that would add the routes is not so protected so I'm
not sure this is actually a solution, more of an extended fudge. In
which case I'm not clear why it is any better than the current
GFP_ATOMIC approach.

> +#define SK_CRIT_ALLOC(sk, flags) ((sk->sk_allocation & __GFP_CRITICAL) | flags)

Lots of hidden conditional logic on critical paths. Also sk should be in
brackets so that the macro evaluation order is defined as should flags

> +#define CRIT_ALLOC(flags) (__GFP_CRITICAL | flags)

Pointless obfuscation

  reply	other threads:[~2005-12-14 11:17 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-12-14  9:12 [RFC][PATCH 3/3] TCP/IP Critical socket communication mechanism Sridhar Samudrala
2005-12-14 11:17 ` Alan Cox [this message]
2005-12-14 12:12   ` Mitchell Blank Jr
2005-12-14 13:18     ` Ingo Oeser
2005-12-14 18:29     ` Sridhar Samudrala
2005-12-14 18:11   ` Sridhar Samudrala
2005-12-14 18:33     ` Ingo Oeser

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