From: Florian Westphal <fw@strlen.de>
To: David Miller <davem@davemloft.net>
Cc: eric.dumazet@gmail.com, fw@strlen.de, netdev@vger.kernel.org,
johannes@sipsolutions.net, linux-wireless@vger.kernel.org
Subject: Re: [PATCH RFC 00/14] shrink skb cb to 44 bytes
Date: Tue, 3 Mar 2015 12:43:02 +0100 [thread overview]
Message-ID: <20150303114302.GE9762@breakpoint.cc> (raw)
In-Reply-To: <20150302.230534.2012113468290945834.davem@davemloft.net>
David Miller <davem@davemloft.net> wrote:
> From: Eric Dumazet <eric.dumazet@gmail.com>
> Date: Mon, 02 Mar 2015 20:02:05 -0800
>
> > About the GRO layout change, reason why 'struct sk_buff *last;' is at
> > the end of struct napi_gro_cb is that this field is not used in fast
> > path.
>
> Understood.
Moved it back to end, thanks!
> While reviewing this I noticed that the jiffies timestamp in GRO cb
> could really be u32 if we want instead of full "unsigned long".
Made it an u16 at the moment -- then __packed is no longer needed
and it fits in 40 bytes.
> > Note : We could try to use one bit in skb to advertise zero shinfo(skb).
> >
> > Many skbs have a zeroed shinfo() (but shinfo->dataref == 1) , and
> > dereferencing skb_shinfo adds a cache line miss.
> >
> > -> We could avoid memset(shinfo, 0, offsetof(struct skb_shared_info,
> > dataref)) & atomic_set(&shinfo->dataref, 1);
> >
> > in alloc_skb() and friends completely.
> >
> > Unfortunately this kind of change would be quite invasive...
>
> Right, all these kinds of things touch everything.
Indeed, but thanks for the hint Eric -- I'll investigate.
prev parent reply other threads:[~2015-03-03 11:43 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1425318028-26531-1-git-send-email-fw@strlen.de>
2015-03-02 17:40 ` [PATCH RFC 04/14] drivers: wireless: rt2x00: move skb_dma to queue entry Florian Westphal
2015-03-02 17:40 ` [PATCH RFC 05/14] drivers: wireless: ar5523: use container_of Florian Westphal
2015-03-03 9:16 ` Pontus Fuchs
2015-03-02 17:40 ` [PATCH RFC 06/14] drivers: wireless: carl9170: shrink carl9170_tx_info Florian Westphal
2015-03-02 17:40 ` [PATCH RFC 07/14] net: wireless: iwlwifi: shrink status private area Florian Westphal
2015-03-02 17:40 ` [PATCH RFC 08/14] net: wireless: mac80211: shrink ieee80211_tx_info Florian Westphal
2015-03-02 18:53 ` Johannes Berg
2015-03-02 19:03 ` Florian Westphal
2015-03-02 19:18 ` Johannes Berg
2015-03-02 19:30 ` Florian Westphal
2015-03-02 17:40 ` [PATCH RFC 09/14] net: wireless: mac80211: shrink private driver area Florian Westphal
2015-03-02 18:52 ` Johannes Berg
2015-03-02 19:49 ` [PATCH RFC 00/14] shrink skb cb to 44 bytes Eric Dumazet
2015-03-02 20:42 ` Florian Westphal
2015-03-02 21:56 ` Eric Dumazet
2015-03-02 22:17 ` David Miller
2015-03-03 4:02 ` Eric Dumazet
2015-03-03 4:05 ` David Miller
2015-03-03 11:43 ` Florian Westphal [this message]
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