From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e39.co.us.ibm.com (e39.co.us.ibm.com [32.97.110.160]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 1679B2C0091 for ; Wed, 5 Feb 2014 11:14:15 +1100 (EST) Received: from /spool/local by e39.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 4 Feb 2014 17:14:10 -0700 Received: from b01cxnp22034.gho.pok.ibm.com (b01cxnp22034.gho.pok.ibm.com [9.57.198.24]) by d01dlp02.pok.ibm.com (Postfix) with ESMTP id 3B1D26E803C for ; Tue, 4 Feb 2014 19:14:03 -0500 (EST) Received: from d01av02.pok.ibm.com (d01av02.pok.ibm.com [9.56.224.216]) by b01cxnp22034.gho.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id s150E7dg6291782 for ; Wed, 5 Feb 2014 00:14:07 GMT Received: from d01av02.pok.ibm.com (localhost [127.0.0.1]) by d01av02.pok.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s150E5aA030508 for ; Tue, 4 Feb 2014 19:14:07 -0500 Date: Tue, 4 Feb 2014 16:13:52 -0800 From: Nishanth Aravamudan To: Christoph Lameter Subject: Re: [PATCH] slub: Don't throw away partial remote slabs if there is no local memory Message-ID: <20140205001352.GC10101@linux.vnet.ibm.com> References: <20140125001643.GA25344@linux.vnet.ibm.com> <20140125011041.GB25344@linux.vnet.ibm.com> <20140127055805.GA2471@lge.com> <20140128182947.GA1591@linux.vnet.ibm.com> <20140203230026.GA15383@linux.vnet.ibm.com> <20140204072630.GB10101@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Cc: Han Pingtian , David Rientjes , penberg@kernel.org, linux-mm@kvack.org, paulus@samba.org, Anton Blanchard , mpm@selenic.com, Joonsoo Kim , linuxppc-dev@lists.ozlabs.org, Wanpeng Li List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 04.02.2014 [14:39:32 -0600], Christoph Lameter wrote: > On Mon, 3 Feb 2014, Nishanth Aravamudan wrote: > > > Yes, sorry for my lack of clarity. I meant Joonsoo's latest patch for > > the $SUBJECT issue. > > Hmmm... I am not sure that this is a general solution. The fallback to > other nodes can not only occur because a node has no memory as his patch > assumes. Thanks, Christoph. I see your point. Something in this area would be nice, though, as it does produce a fairly significant bump in the slab usage on our test system. > If the target node allocation fails (for whatever reason) then I would > recommend for simplicities sake to change the target node to > NUMA_NO_NODE and just take whatever is in the current cpu slab. A more > complex solution would be to look through partial lists in increasing > distance to find a partially used slab that is reasonable close to the > current node. Slab has logic like that in fallback_alloc(). Slubs > get_any_partial() function does something close to what you want. I apologize for my own ignorance, but I'm having trouble following. Anton's original patch did fallback to the current cpu slab, but I'm not sure any NUMA_NO_NODE change is necessary there. At the point we're deactivating the slab (in the current code, in __slab_alloc()), we have successfully allocated from somewhere, it's just not on the node we expected to be on. So perhaps you are saying to make a change lower in the code? I'm not sure where it makes sense to change the target node in that case. I'd appreciate any guidance you can give. Thanks, Nish