Slowdown when copying large files (PR#8624)

[Jeremy Allison]

tl at fairplay.no wrote:

> Hmm, I missed the original post, but this sounds like it could be the bug
> I reported 15 days ago to samba-bugs (PR#8316) and still haven't got any
> responses to.
> 

Sorry, I'm still integrating incoming patches.

> If it's the same bug it's mainly the write performance that's bad, and in
> reality the performance is worse than Win95/WinNT for all files, it's just
> get worse for large files (exactly how much depends on the OS).
> 
> To check if it's the same problem turn up the debug-level to 3, and copy a
> moderately large file to the Samba server from the local disk of a Win98
> workstation. If you get *lots* of SMBwrite and SMBflush in the log-file
> you have the same problem.
> 
> A "good" log created from WinNT features one (or sometimes two) SMBwrite
> per ~63k and zero SMBflush. A log from a Win98 machine features one or two
> SMBwrite per 1.5k (!) and one SMBflush per 1.5k!!!
> 
> Anything above ONE SMBflush per file (at the end) or one SMBwrite per 10k
> or so indicates a serious problem.
> 
> A stop-gap measurement to get *usable* performance is recompile with
> 'NO_FSYNC' defined (or the fsync() call in server.c:sync_file()
> commented).
> 

This is what I'm going to do for 1.9.18p9, but I will
parameterize it.

> This removes the silly 'wait until everything is on disk before continuing
> at every 1.5k', but doesn't fix the small block-size used. The small
> block-size used still limits the performance, but it's actually usable for
> larges files.
> 
> If you can confirm that this is what happens to you too it might be time
> to send it to 'samba-urgent', as it's likely to affect LOTS of people as
> more and more people start using Win98.

Well the problem is the small block size used is *client*
defined - not server. My guess is that the Win98 explorer
is optimised for Web performance, (ie. doing MSS size 
reads/writes) and as the same binary is used for both SMB
file browsing and Web browsing the silly block size has been
used throughout.

Does anyone know if there is a Win98 registry setting to
set the SMB read/write size ?

Jeremy Allison,
Samba Team.
-- 
--------------------------------------------------------
Buying an operating system without source is like buying
a self-assembly Space Shuttle with no instructions.
--------------------------------------------------------