Re: kern/39564: wapbl performance issues with disk cache flushing

[Havard Eidnes <he%uninett.no@localhost>]

The following reply was made to PR kern/39564; it has been noted by GNATS.

From: Havard Eidnes <he%uninett.no@localhost>
To: jmcneill%invisible.ca@localhost
Cc: gnats-bugs%NetBSD.org@localhost, kern-bug-people%netbsd.org@localhost,
 gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost
Subject: Re: kern/39564: wapbl performance issues with disk cache flushing
Date: Mon, 27 Oct 2008 00:52:59 +0100 (CET)

 Hi,
 
 here's some more data on this case.  I increased the amount of
 buffering in lockstat.c to be able to do a lockstat over an
 entire build (increased LOCKSTAT_MAXBUFS tenfold, and bumped
 LOCKSTAT_HASH_SIZE by 8), and with vfs.wapbl.flush_disk_cache=3D0,
 I repeated these two tests:
 
 4) A standard "build.sh -j 16":
 
    6001.172u 2184.995s 29:04.68 469.2%     0+0k 12721+559454io 56360pf+=
 0w
 
 5) as in 4), but with the sync shell loop, 1 second delay:
 
    5751.959u 2341.618s 21:22.68 630.9%     0+0k 8+45947io 32327pf+0w
 
 The corresponding lockstat files are, respectively
 
    ftp://quattro.urc.uninett.no/pub/NetBSD/lockstat.25
 and
    ftp://quattro.urc.uninett.no/pub/NetBSD/lockstat.26
 
 I'm no expert in interpreting the lockstat output, but perhaps
 someone with more experience in the kernel innards can dig out
 some more useful information from this.
 
 Best regards,
 
 - H=E5vard