Messages in this thread | | | Date | Tue, 13 Sep 2005 09:04:32 +0200 | From | Eric Dumazet <> | Subject | Re: "Read my lips: no more merges" - aka Linux 2.6.14-rc1 |
| |
Sonny Rao a écrit : > On Mon, Sep 12, 2005 at 08:34:17PM -0700, Linus Torvalds wrote: > <snip> > >>On the filesystem level, FUSE got merged, and ntfs and xfs got updated. In >>the core VFS layer, the "struct files" thing is now handled with RCU and >>has less expensive locking. > > > I hope this means that people will be more accepting of multi-threaded > benchmarks (who needs real apps... ;-)) which do open() and close(). > > > Yes, no?
If you look at RCU change, you discover they impact read()/write()/... (no more locking), but not open()/dup()/socket() and close() that still take a spinlock to modify the state.
And if your process has many files opened, the cost (read : latency) of open() can be very high, finding a zero bit in a large bit array.
So these RCU changes can help some benchmarks (or real apps... ;-) ), but not some others :)
I wish a process param could allow open() to take any free fd available, not the lowest one. One can always use fcntl(fd, F_DUPFD, slot) to move a fd on a specific high slot and always keep the 64 first fd slots free to speedup the kernel part at open()/dup()/socket() time.
- 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/
| |