* Steven Rostedt (rostedt@xxxxxxxxxxx) wrote: > On Wed, 2010-05-19 at 17:33 +0200, Miklos Szeredi wrote: > > On Wed, 19 May 2010, Linus Torvalds wrote: > > > Btw, since you apparently have a real case - is the "splice to file" > > > always just an append? IOW, if I'm not right in assuming that the only > > > sane thing people would reasonable care about is "append to a file", then > > > holler now. > > > > Virtual machines might reasonably need this for splicing to a disk > > image. > > This comes down to balancing speed and complexity. Perhaps a copy is > fine in this case. > > I'm concerned about high speed tracing, where we are always just taking > pages from the trace ring buffer and appending them to a file or sending > them off to the network. The slower this is, the more likely you will > lose events. > > If the "move only on append to file" is easy to implement, I would > really like to see that happen. The speed of splicing a disk image for a > virtual machine only impacts the patience of the user. The speed of > splicing tracing output, impacts how much you can trace without losing > events. I'm with Steven here. I only care about appending full pages at the end of a file. If possible, I'd also like to steal back the pages after waiting for the writeback I/O to complete so we can put them back in the ring buffer without stressing the page cache and the page allocator needlessly. Thanks, Mathieu -- Mathieu Desnoyers Operating System Efficiency R&D Consultant EfficiOS Inc. http://www.efficios.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>