Subject: Re: PATCH 23/10]Optimize the upload speed for PPP connection.

From: William Allen Simpson <[email-masked]>
Date: Fri, 23 Oct 2009 07:46:08 -0400

fangxiaozhi 00110321 wrote:
> From: fangxiaozhi <[email-masked]>
> 1. This patch is based on the kernel of 2.6.32-rc4 
> 2. In this patch, we enlarge the out buffer size to optimize the upload speed for the ppp connection. Then it can support the upload of HSUPA data cards.
> Signed-off-by: fangxiaozhi <[email-masked]>
> -----------------------------------------------------------------------------------------
> --- a/drivers/net/ppp_async.c	2009-10-12 05:43:56.000000000 +0800
> +++ b/drivers/net/ppp_async.c	2009-10-15 16:29:56.000000000 +0800
> @@ -36,7 +36,7 @@
>  
>  #define PPP_VERSION	"2.4.2"
>  
> -#define OBUFSIZE	256
> +#define OBUFSIZE	2048
>  
>  /* Structure for storing local state. */
>  struct asyncppp {
> 
Concur.  I'd go further than that, my code usually made room for at least
a full MTU (MRU) with HDLC escaping.  To minimize context switches, that
should be 3014 ((1500 MRU + 2 FCS + 4 header) * 2 escapes + 2 flags).

Even in the old days, when memory was tight, context switches and interrupt
time were more expensive, too.  PPP is supposed to scale to OC-192.