> Of course. I meant that if you are reading, for example, some status register
> in a loop waiting for "ready bit" set, the memory barrier won't help you
> to notice this event any faster. Actually you'll notice that *later*, as
> "mb" is expensive.
I think you need an mb here. To force sychronization with other CPUs.
Unless you know you are UP or there is no possibility another CPU may
access the relevant device.
Of course mbs hit performance but it's a trade off for coherency.
-- + Maciej W. Rozycki, Technical University of Gdansk, Poland + +--------------------------------------------------------------+ + e-mail: macro@ds2.pg.gda.pl, PGP key available +- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/