Re: Status of buffered write path (deadlock fixes)

Trond Myklebust wrote:

On Wed, 2006-12-13 at 12:56 +1100, Nick Piggin wrote:

Note that these pages should be *really* rare. Definitely even for normal
filesystems I think RMW would use too much bandwidth if it were required
for any significant number of writes.

If file "foo" exists on the server, and contains data, then something
like

fd = open("foo", O_WRONLY);
write(fd, "1", 1);

should never need to trigger a read. That's a fairly common workload
when you think about it (happens all the time in apps that do random
write).

I have to admit that I've only been paying attention with one eye, but
why doesn't this require a read?  If "foo" is non-zero in size, then
how does the client determine how much data in the buffer to write to
the server?

Isn't RMW required for any i/o which is either not buffer aligned or
a multiple of the buffer size?

   Thanx...

      ps
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

---

• Follow-Ups:
  • Re: Status of buffered write path (deadlock fixes)
    • From: Trond Myklebust <[email protected]>

• References:
  • Status of buffered write path (deadlock fixes)
    • From: Nick Piggin <[email protected]>
  • Re: Status of buffered write path (deadlock fixes)
    • From: Mark Fasheh <[email protected]>
  • Re: Status of buffered write path (deadlock fixes)
    • From: Nick Piggin <[email protected]>
  • Re: Status of buffered write path (deadlock fixes)
    • From: Mark Fasheh <[email protected]>
  • Re: Status of buffered write path (deadlock fixes)
    • From: Nick Piggin <[email protected]>
  • Re: Status of buffered write path (deadlock fixes)
    • From: Nick Piggin <[email protected]>
  • Re: Status of buffered write path (deadlock fixes)
    • From: Mark Fasheh <[email protected]>
  • Re: Status of buffered write path (deadlock fixes)
    • From: Nick Piggin <[email protected]>
  • Re: Status of buffered write path (deadlock fixes)
    • From: Trond Myklebust <[email protected]>
  • Re: Status of buffered write path (deadlock fixes)
    • From: Nick Piggin <[email protected]>
  • Re: Status of buffered write path (deadlock fixes)
    • From: Trond Myklebust <[email protected]>

• Prev by Date: [patch] Add allowed_affinity to the irq_desc to make it possible to have restricted irqs
• Next by Date: Re: isochronous receives?
• Previous by thread: Re: Status of buffered write path (deadlock fixes)
• Next by thread: Re: Status of buffered write path (deadlock fixes)
• Index(es):
  • Date
  • Thread

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]