From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicholas Van Orton Subject: Re: can we reuse an skb Date: Fri, 19 Jun 2009 15:41:20 +0530 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: jon_zhou@agilent.com, radhamohan_ch@yahoo.com, netdev@vger.kernel.org To: Peter Chacko Return-path: Received: from mail-px0-f189.google.com ([209.85.216.189]:43172 "EHLO mail-px0-f189.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754584AbZFSKLS (ORCPT ); Fri, 19 Jun 2009 06:11:18 -0400 Received: by pxi27 with SMTP id 27so1690108pxi.33 for ; Fri, 19 Jun 2009 03:11:21 -0700 (PDT) Sender: netdev-owner@vger.kernel.org List-ID: On Fri, 2009-06-19 at 12:51 +0530, Peter Chacko wrote: Radha, > > skb memory is coming from slab allocation pool, which itself are > re-usable pools. kmalloc(ATOMIC) on these object caches don't incur > much penalty as think for a case when it does memory > allocation/de-allocation. So the intelligence you want to put in the > driver is already done by slab layer. But if you want to add some > thing like per-flow ring-buffers, optimized for a point-to-point link > or similar purpose, you can have a driver level cache . Does this mean that when skb buffer has been allocated using dev_alloc_skb(), filled with received data and passed to the upper layers the kernel would automatically do the task of releasing this buffer without the user calling dev_kfree_skb()? I once got KERNEL: assertion (!atomic_read(&skb->users)) failed at net/core/dev.c errors when trying to free them using dev_kfree_skb() Could this be cause I did not wait until netif_rx_completed() was called? Regards, Nicholas > > thanks > > On Fri, Jun 19, 2009 at 12:21 PM, wrote: > > I am also thinking about this... > > > > i.e.pcnet32.c > > seems the skb will be claimed to be unuseful(mark some bits) in the device driver, than it will be recycled in the softirq handler, > > > > that means unable to reuse it, unless modidy the driver. > > > > Regards, > > zhou rui > > > > -----Original Message----- > > From: netdev-owner@vger.kernel.org [mailto:netdev-owner@vger.kernel.org] On Behalf Of Radha Mohan > > Sent: Friday, June 19, 2009 2:47 PM > > To: netdev@vger.kernel.org > > Subject: can we reuse an skb > > > > > > Hi, > > > > For an ethernet driver, we need to allocate some pool of SKBs for receiving packets. Is there any way we can reuse the same SKBs without the need to re-allocate in atomic every time one has been used up for netif_rx(). > > > > Any pointers will be helpful. > > > > -- Mohan > > > > > > ICC World Twenty20 England '09 exclusively on YAHOO! CRICKET http://cricket.yahoo.com > > > > -- > > To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > > > -- > > To unsubscribe from this list: send the line "unsubscribe netdev" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html