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Date: Tue, 19 Jun 2007 16:11:55 -0700 From: "Waskiewicz Jr, Peter P" <peter.p.waskiewicz.jr@...el.com> To: "David Miller" <davem@...emloft.net> Cc: <netdev@...r.kernel.org>, <jeff@...zik.org>, "Kok, Auke-jan H" <auke-jan.h.kok@...el.com>, <hadi@...erus.ca>, <kaber@...sh.net> Subject: RE: [PATCH 3/3] NET: [CORE] Stack changes to add multiqueue hardware support API > It's not being allocated at "compile time", it's being > allocated linearly into one block of ram in order to avoid > pointer derefs but it's still "dynamic" in that the size > isn't known until the alloc_netdev() call. > > We do this trick all over the networking, TCP sockets are 3 > or 4 different structures, all allocated into a linear block > of memory so that: > > 1) only one memory allocation needs to be done for each object > create, this is not relevant for the net_device case > except in extreme examples bringing thousands of devices > up and down which I suppose someone can give a realistic > example of :-) > > 2) each part can be accessed as an offset from the other instead > of a pointer deref which costs a cpu memory read > > Please change the allocation strategy as I recommended, thanks. Later this afternoon someone in my group came over and bonked me in the head, and made this obvious to me. Thanks for the follow-up; great catch on the efficiency. It's in my code now and is currently running some test passes. Thanks Dave, -PJ Waskiewicz - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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