-----Original Message----- From: Yang, Steve Sent: Thursday, October 12, 2006 5:46 PM To: 'Stephen Hemminger' Cc: netdev@vger.kernel.org Subject: RE: [patch] Performance enhancement patches for SB1250 MAC
Stephen, I assume the "expense" you referred to is the reserved SK cache buffers. 1. The SKB_CACHE does hold on to buffers which would otherwise be returned to the system (although the number it holds on to is limited and configurable). These buffers are only returned with certainty at module unload time, although with normal traffic most of them would be recycled pretty quick. I think the cache was implemented as a stack, rather than a FIFO, which could cause a few buffers to be held for quite a while under light loads. 2. SKB_CACHE, just like NAPI, is also a configurable option. Systems that need the performance have the option of turning this on, at the expense of small number of buffers; other systems which don't care much about networking performance can leave this option off. 3. Can you elaborate other possible issues that you touch upon (memory starvation/race, etc.)? Regards, Steve Yang -----Original Message----- From: Stephen Hemminger [mailto:[EMAIL PROTECTED] Sent: Thursday, October 12, 2006 3:14 PM To: Yang, Steve Cc: netdev@vger.kernel.org Subject: Re: [patch] Performance enhancement patches for SB1250 MAC On Thu, 12 Oct 2006 14:54:33 -0700 "Yang, Steve" <[EMAIL PROTECTED]> wrote: > FYI ... > > Regards, > Steve Yang > > -----Original Message----- > From: Yang, Steve > Sent: Monday, September 25, 2006 3:50 PM > To: '[EMAIL PROTECTED]' > Cc: '[EMAIL PROTECTED]'; 'Mark E Mason' > Subject: Performance enhancement patches for SB1250 MAC > > Hi, > > The attached are two network performance enhancement patches for > SB1250 MAC. The NAPI patch applies first. Followed by the "skb cache" patch. > They applied and builds cleanly on 2.6.18 kernel for the following > kernel option combinations: > > SBMAC_NAPI no yes yes > SKB_CACHE no no yes > > Regards, > Steve Yang > NAK on the SKB_CACHE it is idea that just ends up favoring your driver at the expense of the rest of the system. Also, there are resource/memory starvation issues and probably other races as well. I bet it makes your benchmark run faster, but it doesn't belong in normal kernel -- Stephen Hemminger <[EMAIL PROTECTED]> - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
