[lkml]   [2007]   [Jan]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: O_DIRECT question
Michael Tokarev wrote:
> Linus Torvalds wrote:
>> On Thu, 11 Jan 2007, Viktor wrote:
>>> OK, madvise() used with mmap'ed file allows to have reads from a file
>>> with zero-copy between kernel/user buffers and don't pollute cache
>>> memory unnecessarily. But how about writes? How is to do zero-copy
>>> writes to a file and don't pollute cache memory without using O_DIRECT?
>>> Do I miss the appropriate interface?
>> mmap()+msync() can do that too.
> It can, somehow... until there's an I/O error. And *that* is just terrbile.

The other problem besides the inability to handle IO errors is that
mmap()+msync() is synchronous. You need to go async to keep the
pipelines full.

Now if someone wants to implement an aio version of msync and mlock,
that might do the trick. At least for MMU systems. Non MMU systems
just can't play mmap type games.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2007-01-12 00:27    [W:0.168 / U:5.560 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site