Hello U can download coreutils from gnu.org. Sent from my HTC -- Send Kernelnewbies mailing list submissions to kernelnewbies@kernelnewbies.org To subscribe or unsubscribe via the World Wide Web, visit http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies or, via email, send a message with subject or body 'help' to kernelnewbies-request@kernelnewbies.org You can reach the person managing the list at kernelnewbies-owner@kernelnewbies.org When replying, please edit your Subject line so it is more specific than "Re: Contents of Kernelnewbies digest..." Message: 1 Date: Thu, 21 Jun 2012 18:17:36 +0800 From: ?? <lovelylich@gmail.com> Subject: Re: [RFC] tcp: How does SACK or FACK determine the time to start fast retransmition? To: Vijay Subramanian <subramanian.vijay@gmail.com> Cc: netdev <netdev@vger.kernel.org>, kernelnewbies@kernelnewbies.org Message-ID: <4FE2F4C0.4020900@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed ? 2012/6/21 16:42, Vijay Subramanian ??:

With SACK, number of dupacks does not have much meaning. What matters is --how the SACK scoreboard looks like i.e. which packets are tagged Lost/Sacked/Retransmitted -- Whether FACK is in use (this assumes holes in between sacked packets are lost and have left the network and so we can send out more packets)

So, stack does not count the number of dupacks that have come in. Only SACK blocks matter. You can try to track the following path: tcp_ack() deals with incoming acks and if it sees a dupack (does not matter what number), or incoming packet contains SACK it calls tcp_fastretrans_alert() which calls tcp_xmit_retransmit_queue().

tcp_xmit_retransmit_queue() decides which packets to retransmit. The first packet to start retransmitting from is tracked in tp->retransmit_skb_hint. Note that the dupThresh is actually tracked by tp->reordering which measures the reordering in the network and is not fixed at 3. So, if more than tp->reordering packets have been acked above a given packet, this packet is a candidate for retransmisson. See tcp_mark_head_lost() to see how the reordering metric is used to mark packets as lost. This corresponds to the check you mentioned in the RFC.

So, window permitting, packets are sent as follows; (a)-- Packets marked lost as per description above (b)-- new packets (if any) (c)-- Holes between sacked packets which are not reliably lost.

choice between (b) and (c) is made in tcp_can_forward_retransmit().

Hope this helps. Vijay

It is just I wanted! Thanks for your detailed explaination and kindness. ------------------------------ Message: 2 Date: Thu, 21 Jun 2012 17:57:22 +0530 From: Vijay Chauhan <kernel.vijay@gmail.com> Subject: Kernel Memory To: kernelnewbies@kernelnewbies.org Message-ID: <CAJ61zBA++CFmTHSb2cRr=cKJdTkVYsSVs3_igESbbf21gWaqCQ@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Hello, I am newbie. It has been said "kernel memory is not pageable" What does it mean? There is no concept of kernel virtual address? Any simple explanation will help me to udnerstand. Thanks, Vijay ------------------------------ Message: 3 Date: Thu, 21 Jun 2012 20:48:48 +0800 From: ?? <wangzhe5004@gmail.com> Subject: download the source code of some commands To: kernelnewbies <kernelnewbies@kernelnewbies.org> Message-ID: <CAJrRU3VHh719vZgCCJ3r8K842YemEo9d5_0swgqsGDNXE0vxVQ@mail.gmail.com> Content-Type: text/plain; charset="iso-8859-1" Hi all: I want to see some source code of some commands,for example,halt,reboot,uptime,and so on. but i don't kown where to download? can you give me some advice? Thanks in advance!