Messages in this thread | | | Subject | Re: Opinion on ordering of writel vs. stores to RAM | From | Benjamin Herrenschmidt <> | Date | Tue, 12 Sep 2006 17:17:00 +1000 |
| |
> If I see an io_to_io_barrier(), how am I to tell if it is > read to read, write to write, read to write, write to read, > read/write to read, read/write to write, read to read/write, > write to read/write, or read/write to read/write? > > Considering just reads and writes to MMIO, there are > 9 possible types of fence. SPARC seems to cover a > decent number of these distinctly; the instruction takes > an immediate value as flags.
We need to decide wether a single one doing a full MMIO fence (and not memory) is enough or if the performance different justifies maybe having io_to_io_{wmb,rmb,mb}. I don't see any real use for more combinations.
David ? It's your call here. What do you think ?
Ben.
- 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/
| |