[lkml]   [2005]   [Dec]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: [RFC][PATCH 0/3] TCP/IP Critical socket communication mechanism
    On Thu, 15 Dec 2005 18:09:22 -0800
    Sridhar Samudrala <> wrote:

    > On Thu, 2005-12-15 at 00:21 -0800, David S. Miller wrote:
    > > From: Sridhar Samudrala <>
    > > Date: Wed, 14 Dec 2005 23:37:37 -0800 (PST)
    > >
    > > > Instead, you seem to be suggesting in_emergency to be set dynamically
    > > > when we are about to run out of ATOMIC memory. Is this right?
    > >
    > > Not when we run out, but rather when we reach some low water mark, the
    > > "critical sockets" would still use GFP_ATOMIC memory but only
    > > "critical sockets" would be allowed to do so.
    > >
    > > But even this has faults, consider the IPSEC scenerio I mentioned, and
    > > this applies to any kind of encapsulation actually, even simple
    > > tunneling examples can be concocted which make the "critical socket"
    > > idea fail.
    > >
    > > The knee jerk reaction is "mark IPSEC's sockets critical, and mark the
    > > tunneling allocations critical, and... and..." well you have
    > > GFP_ATOMIC then my friend.
    > I would like to mention another reason why we need to have a new
    > GFP_CRITICAL flag for an allocation request. When we are in emergency,
    > even the GFP_KERNEL allocations for a critical socket should not
    > sleep. This is because the swap device may have failed and we would
    > like to communicate this event to a management server over the
    > critical socket so that it can initiate the failover.
    > We are not trying to solve swapping over network problem. It is much
    > simpler. The critical sockets are to be used only to send/receive
    > a few critical messages reliably during a short period of emergency.

    If it is only one place, why not pre-allocate one "I'm sick now"
    skb and hold onto it. Any bigger solution seems to snowball into
    a huge mess.

    Stephen Hemminger <>
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at

     \ /
      Last update: 2005-12-16 18:51    [W:0.024 / U:0.772 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site