hi, > > Does using splice would really do help in performance much? > > Since the performance improvement might comes from two advantage: > > 1. no going to user space. > > 2. no memory copy > > splice surely have advantage 1, but doest it have the > > second? Can we avoid memory copy with splice, while > > writing files to samba? (scatter-gather in block write?) > > Just to get things straight: Recently I've seen a Xeon box > ship almost 500 megabytes (!) per second to smbclient using > a single SMB connection via > RAMdisk->smbd->10GigE->smbclient->/dev/null. This was > without sendfile. So unless you want to squeeze the last 5% > out of a heavily loaded server, I'd say the advantages of > sendfile/recvfile are close to negligible. I might be wrong well, in my condition, it might be 30% instead of 5%, IF splice can cover advantage 1 and 2. 1. I'm using a slow CPU (FA526) , and the memory copy is even slower. 2. The reading performance is over 7 MB/s, with mmap and sendfile enabled, while writing is only 4-5 MB/s. Without mmap and sendfile, reading from samba is also about 4-5 MB/s. 3. I used Oprofile to profile writing file to samba and found that CPU takes over 30% CPU time on copy_from/to_user, so I think going to user space and back again is the bottleneck. 4. My device is only 100Mbps Ethernet 5. I uses Windows client to measure throughput
> here, but the network latencies together with non-optimally > queued requests by the client have a MUCH greater influence. 1. If splice works, can memory copy be avoided? 2. Sorry I don't really get what the "non-optimally queued requests" means. And what could I do to make it optimized? Thanks. Best Regards, Mac Lin _________________________________________________________________ 5 GB 超大容量 、創新便捷、安全防護垃圾郵件和病毒 — 立即升級 Windows Live Hotmail http://mail.live.com -- To unsubscribe from this list go to the following URL and read the instructions: https://lists.samba.org/mailman/listinfo/samba
