Quoting r. Sean Hefty <[EMAIL PROTECTED]>: > Subject: Re: Re: [PATCH (updated)] ipoib: dont lock tx on completion > > Michael S. Tsirkin wrote: > > >>I don't see a specific race -- I'm just not totally comfortable yet, > >>even with that fixed. The issue is not necessarily reads being > >>delayed, since both an out-of-order CPU and a compiler may move reads > >>much _earlier_ than they appear in the code (for example a read may be > >>speculatively executed because of branch prediction for a test in an > >>if statement). > >> > >>- R. > >> > >Can they be moved to before the wmb? I think not. > > Given that there's some concern here regarding races, what sort of > performance improvement do we see with this change? > > - Sean >
Nothing major, I expect, especially given that only the send flow is affected, and that is already apparently using less CPU than receive. But I am just thinking, with tx_head/tx_taiil we have a circular buffer here, how come we can not use it without races and locks? There must be a way ... -- MST - Michael S. Tsirkin _______________________________________________ openib-general mailing list [email protected] http://openib.org/mailman/listinfo/openib-general To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general
