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Message-ID: <alpine.LFD.2.00.1207222314230.2458@ja.ssi.bg> Date: Sun, 22 Jul 2012 23:34:38 +0300 (EEST) From: Julian Anastasov <ja@....bg> To: David Miller <davem@...emloft.net> cc: netdev@...r.kernel.org Subject: Re: [PATCH RFC] tcp: use seqlock for all cached tcp_metrics Hello, On Sun, 22 Jul 2012, David Miller wrote: > From: Julian Anastasov <ja@....bg> > Date: Sun, 22 Jul 2012 12:44:28 +0300 > > > The ability to reclaim existing cache entries > > requires metrics to be accessed with additional seqlock. > > fastopen_cache tried to provide such locking for its values > > but there is always the risk to access reclaimed entry. > > I basically claim that accidental use of reclaimed entries > is completely harmless for everything other than fastopen. > > Therefore I do not advocate adding the new overhead and complexity for > the non-fastopen cases. It should be a completely free, lockless, and > synchornization free cache. If we read crap metrics, so be it, maybe > the network dynamics changed to the same amount, and we would never > know the different. Therefore, it doesn't really matter if we read > crap values for these measurements. OK, it seems I didn't understand you fully in previous email. So, I can just send patch (or 2) for the tcpm_stamp and tcp_tw_remember_stamp problems, now or after 2 weeks? > Thanks. Regards -- Julian Anastasov <ja@....bg> -- 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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