diff options
Diffstat (limited to 'docs/docbook/projdoc/Speed.sgml')
| -rw-r--r-- | docs/docbook/projdoc/Speed.sgml | 238 |
1 files changed, 236 insertions, 2 deletions
diff --git a/docs/docbook/projdoc/Speed.sgml b/docs/docbook/projdoc/Speed.sgml index 55d8b9492b..17adf10429 100644 --- a/docs/docbook/projdoc/Speed.sgml +++ b/docs/docbook/projdoc/Speed.sgml @@ -54,6 +54,92 @@ systems. </sect1> <sect1> +<title>Oplocks</title> + +<sect2> +<title>Overview</title> + +<para> +Oplocks are the way that SMB clients get permission from a server to +locally cache file operations. If a server grants an oplock +(opportunistic lock) then the client is free to assume that it is the +only one accessing the file and it will agressively cache file +data. With some oplock types the client may even cache file open/close +operations. This can give enormous performance benefits. +</para> + +<para> +With the release of Samba 1.9.18 we now correctly support opportunistic +locks. This is turned on by default, and can be turned off on a share- +by-share basis by setting the parameter : +</para> + +<para> +<command>oplocks = False</command> +</para> + +<para> +We recommend that you leave oplocks on however, as current benchmark +tests with NetBench seem to give approximately a 30% improvement in +speed with them on. This is on average however, and the actual +improvement seen can be orders of magnitude greater, depending on +what the client redirector is doing. +</para> + +<para> +Previous to Samba 1.9.18 there was a 'fake oplocks' option. This +option has been left in the code for backwards compatibility reasons +but it's use is now deprecated. A short summary of what the old +code did follows. +</para> + +</sect2> + +<sect2> +<title>Level2 Oplocks</title> + +<para> +With Samba 2.0.5 a new capability - level2 (read only) oplocks is +supported (although the option is off by default - see the smb.conf +man page for details). Turning on level2 oplocks (on a share-by-share basis) +by setting the parameter : +</para> + +<para> +<command>level2 oplocks = true</command> +</para> + +<para> +should speed concurrent access to files that are not commonly written +to, such as application serving shares (ie. shares that contain common +.EXE files - such as a Microsoft Office share) as it allows clients to +read-ahread cache copies of these files. +</para> + +</sect2> + +<sect2> +<title>Old 'fake oplocks' option - deprecated</title> + +<para> +Samba can also fake oplocks, by granting a oplock whenever a client +asks for one. This is controlled using the smb.conf option "fake +oplocks". If you set "fake oplocks = yes" then you are telling the +client that it may agressively cache the file data for all opens. +</para> + +<para> +Enabling 'fake oplocks' on all read-only shares or shares that you know +will only be accessed from one client at a time you will see a big +performance improvement on many operations. If you enable this option +on shares where multiple clients may be accessing the files read-write +at the same time you can get data corruption. +</para> + +</sect2> +</sect1> + +<sect1> <title>Socket options</title> <para> @@ -141,6 +227,55 @@ In most cases the default is the best option. </sect1> <sect1> +<title>Locking</title> + +<para> +By default Samba does not implement strict locking on each read/write +call (although it did in previous versions). If you enable strict +locking (using "strict locking = yes") then you may find that you +suffer a severe performance hit on some systems. +</para> + +<para> +The performance hit will probably be greater on NFS mounted +filesystems, but could be quite high even on local disks. +</para> + +</sect1> + +<sect1> +<title>Share modes</title> + +<para> +Some people find that opening files is very slow. This is often +because of the "share modes" code needed to fully implement the dos +share modes stuff. You can disable this code using "share modes = +no". This will gain you a lot in opening and closing files but will +mean that (in some cases) the system won't force a second user of a +file to open the file read-only if the first has it open +read-write. For many applications that do their own locking this +doesn't matter, but for some it may. Most Windows applications +depend heavily on "share modes" working correctly and it is +recommended that the Samba share mode support be left at the +default of "on". +</para> + +<para> +The share mode code in Samba has been re-written in the 1.9.17 +release following tests with the Ziff-Davis NetBench PC Benchmarking +tool. It is now believed that Samba 1.9.17 implements share modes +similarly to Windows NT. +</para> + +<para> +NOTE: In the most recent versions of Samba there is an option to use +shared memory via mmap() to implement the share modes. This makes +things much faster. See the Makefile for how to enable this. +</para> + +</sect1> + +<sect1> <title>Log level</title> <para> @@ -152,6 +287,18 @@ expensive. </sect1> <sect1> +<title>Wide lines</title> + +<para> +The "wide links" option is now enabled by default, but if you disable +it (for better security) then you may suffer a performance hit in +resolving filenames. The performance loss is lessened if you have +"getwd cache = yes", which is now the default. +</para> + +</sect1> + +<sect1> <title>Read raw</title> <para> @@ -193,6 +340,61 @@ case you may wish to change this option. </sect1> <sect1> +<title>Read prediction</title> + +<para> +Samba can do read prediction on some of the SMB commands. Read +prediction means that Samba reads some extra data on the last file it +read while waiting for the next SMB command to arrive. It can then +respond more quickly when the next read request arrives. +</para> + +<para> +This is disabled by default. You can enable it by using "read +prediction = yes". +</para> + +<para> +Note that read prediction is only used on files that were opened read +only. +</para> + +<para> +Read prediction should particularly help for those silly clients (such +as "Write" under NT) which do lots of very small reads on a file. +</para> + +<para> +Samba will not read ahead more data than the amount specified in the +"read size" option. It always reads ahead on 1k block boundaries. +</para> + +</sect1> + +<sect1> +<title>Memory mapping</title> + +<para> +Samba supports reading files via memory mapping them. One some +machines this can give a large boost to performance, on others it +makes not difference at all, and on some it may reduce performance. +</para> + +<para> +To enable you you have to recompile Samba with the -DUSE_MMAP option +on the FLAGS line of the Makefile. +</para> + +<para> +Note that memory mapping is only used on files opened read only, and +is not used by the "read raw" operation. Thus you may find memory +mapping is more effective if you disable "read raw" using "read raw = +no". +</para> + +</sect1> + +<sect1> <title>Slow Clients</title> <para> @@ -308,12 +510,11 @@ drive (Kernel 2.0.30). The transfer rate was reasonable for 10 baseT. </para> <para> -<programlisting> +FIXME The figures are: Put Get P166 client 3Com card: 420-440kB/s 500-520kB/s P100 client 3Com card: 390-410kB/s 490-510kB/s DX4-75 client NE2000: 370-380kB/s 330-350kB/s -</programlisting> </para> <para> @@ -341,4 +542,37 @@ staggering. </para> </sect1> + +<sect1> +<title>My Results</title> + +<para> +Some people want to see real numbers in a document like this, so here +they are. I have a 486sx33 client running WfWg 3.11 with the 3.11b +tcp/ip stack. It has a slow IDE drive and 20Mb of ram. It has a SMC +Elite-16 ISA bus ethernet card. The only WfWg tuning I've done is to +set DefaultRcvWindow in the [MSTCP] section of system.ini to 16384. My +server is a 486dx3-66 running Linux. It also has 20Mb of ram and a SMC +Elite-16 card. You can see my server config in the examples/tridge/ +subdirectory of the distribution. +</para> + +<para> +I get 490k/s on reading a 8Mb file with copy. +I get 441k/s writing the same file to the samba server. +</para> + +<para> +Of course, there's a lot more to benchmarks than 2 raw throughput +figures, but it gives you a ballpark figure. +</para> + +<para> +I've also tested Win95 and WinNT, and found WinNT gave me the best +speed as a samba client. The fastest client of all (for me) is +smbclient running on another linux box. Maybe I'll add those results +here someday ... +</para> + +</sect1> </chapter> |