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From: "Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi>
To: Jan Engelhardt <jengelh@computergmbh.de>
Cc: Patrick McHardy <kaber@trash.net>,
	Netdev <netdev@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	David Miller <davem@davemloft.net>,
	Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: Re: [RFC PATCH 3/8] [NET]: uninline dev_alloc_skb, de-bloats a lot
Date: Wed, 12 Mar 2008 17:27:16 +0200 (EET)	[thread overview]
Message-ID: <Pine.LNX.4.64.0803121711400.24534@kivilampi-30.cs.helsinki.fi> (raw)
In-Reply-To: <Pine.LNX.4.64.0802202135080.32171@kivilampi-30.cs.helsinki.fi>

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On Thu, 21 Feb 2008, Ilpo Järvinen wrote:

> On Wed, 20 Feb 2008, Jan Engelhardt wrote:
> 
> > On Feb 20 2008 17:27, Patrick McHardy wrote:
> >
> > > __dev_alloc_skb() is also an inline function which performs
> > > some extra work. Which raises the question - if dev_alloc_skb()
> >
> > I'd like to see the results when {__dev_alloc_skb is externed
> > and dev_alloc_skb remains inlined}.
> 
> The results are right under your nose already... ;-)
> See from the list of the series introduction:
> 
>   http://marc.info/?l=linux-netdev&m=120351526210711&w=2
> 
> IMHO more interesting number (which I currently don't have) is the 
> _remaining_ benefits of uninlining __dev_alloc_skb after
> dev_alloc_skb was first uninlined.

I've measured this now... Without many debug CONFIGs (in v2.6.25-rc2-mm1), 
the dev_alloc_skb is much less than 23kB:

    382 funcs, 157 +, 12335 -, diff: -12178 --- dev_alloc_skb
    dev_alloc_skb                 |  +37

...and on top of that, I got only this:
    48 funcs, 111 +, 836 -, diff: -725 --- __dev_alloc_skb

Not that impressive compared with many much worse cases (wasn't a big 
surprise because there were fewer callsites for the latter).

Anyway, would I uninline it (or one some another function that has such 
two variants that are good candidates for uninlining), should I try to 
avoid deepening the call-chain by two functions? To me it seems that only 
way to fool gcc to do that for sure would be using some trick like this:
Rename __dev_alloc_skb to ___dev_alloc_skb in the header (with appropriate
don't ever call this due to bloat comment added) and both __dev_alloc_skb 
and dev_alloc_skb could then be made to call that one in .c file. 
Otherwise I'm not that sure gcc wouldn't try to be too clever if I just 
use inline in .c file.

-- 
 i.

  reply	other threads:[~2008-03-12 15:27 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-20 13:47 [RFC PATCH 0/8]: uninline & uninline Ilpo Järvinen
2008-02-20 13:47 ` [RFC PATCH 1/8] [NET]: uninline skb_put, de-bloats a lot Ilpo Järvinen
2008-02-20 13:47   ` [RFC PATCH 2/8] [NET]: uninline skb_pull, " Ilpo Järvinen
2008-02-20 13:47     ` [RFC PATCH 3/8] [NET]: uninline dev_alloc_skb, " Ilpo Järvinen
2008-02-20 13:47       ` [RFC PATCH 4/8] [NET]: uninline skb_push, " Ilpo Järvinen
2008-02-20 13:47         ` [RFC PATCH 5/8] [NET]: uninline dst_release Ilpo Järvinen
2008-02-20 13:47           ` [RFC PATCH 6/8] [NET]: uninline skb_trim, de-bloats Ilpo Järvinen
2008-02-20 13:47             ` [RFC PATCH 7/8] [SCTP]: uninline sctp_add_cmd_sf Ilpo Järvinen
2008-02-20 13:47               ` [RFC PATCH 8/8] Jhash in too big for inlining, move under lib/ Ilpo Järvinen
2008-02-23  8:02                 ` Andrew Morton
2008-02-23 10:05                   ` Ilpo Järvinen
2008-02-23 18:21                     ` Andrew Morton
2008-02-23 13:06                   ` Andi Kleen
2008-02-20 22:16               ` [RFC PATCH 7/8] [SCTP]: uninline sctp_add_cmd_sf Vlad Yasevich
2008-02-20 22:34                 ` Ilpo Järvinen
2008-02-21 15:27                   ` Vlad Yasevich
2008-02-20 16:19       ` [RFC PATCH 3/8] [NET]: uninline dev_alloc_skb, de-bloats a lot Jan Engelhardt
2008-02-20 16:27         ` Patrick McHardy
2008-02-20 16:30           ` Jan Engelhardt
2008-02-20 22:18             ` Ilpo Järvinen
2008-03-12 15:27               ` Ilpo Järvinen [this message]
2008-02-20 13:54   ` [RFC PATCH 1/8] [NET]: uninline skb_put, " Patrick McHardy
2008-02-20 13:57   ` Eric Dumazet
2008-02-23  8:02 ` [RFC PATCH 0/8]: uninline & uninline Andrew Morton
2008-02-23 10:11   ` Ilpo Järvinen
2008-02-23 13:15   ` Andi Kleen
2008-02-23 18:06     ` Ilpo Järvinen
2008-02-23 18:55     ` Andrew Morton
2008-02-23 19:58       ` Hua Zhong
2008-02-23 21:02         ` Andi Kleen
2008-02-27 19:08       ` profile-likely patch (was " Valdis.Kletnieks

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