Re: msync() behaviour broken for MS_ASYNC, revert patch?

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 

Andrew Morton wrote:

Nick Piggin <[email protected]> wrote:



and had no need for a MS_SYNC anywhere in the meantime.
If you did have the need for MS_SYNC, then kicking off the IO
ASAP is going to be more efficient.



Of course these sorts of applications don't know what they'll be doing in
the future.  Often the location of the next update is driven by something
which came across the network.



If there is no actual need for the application to start a write (eg
for data integrity) then why would it ever do that?



There's no need to do that.   Look:

msync(MS_ASYNC): propagate pte dirty flags into pagecache

LINUX_FADV_ASYNC_WRITE: start writeback on all pages in region which are
dirty and which aren't presently under writeback.

LINUX_FADV_WRITE_WAIT: wait on writeback of all pages in range.

I think that covers all conceivable scenarios.  One thing per operation,
leave the decisions and tuning up to the application.  And it gives us two
operations which are also useful in association with regular write().



Oh yeah it is easy if you want to define some more APIs and do
it in a Linux specific way.

But the main function of msync(MS_ASYNC) AFAIK is to *start* IO.
Why do we care so much if some application goes stupid with it?
Why not introduce a linux specific MS_flag to propogate pte dirty
bits?

--
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com - 
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/
[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]
  Powered by Linux