Date: Wed, 14 Jul 2010 09:04:54 +0200 From: Gary Jennejohn <gljennjohn@googlemail.com> To: Jerry Toung <jrytoung@gmail.com> Cc: freebsd-hackers@freebsd.org Subject: Re: disk I/O, VFS hirunningspace Message-ID: <20100714090454.1177b96b@ernst.jennejohn.org> In-Reply-To: <AANLkTinm3kFm7pF_cxoNz1Cgyd5UvnmgZzCpbjak-zzy@mail.gmail.com> References: <AANLkTinm3kFm7pF_cxoNz1Cgyd5UvnmgZzCpbjak-zzy@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Tue, 13 Jul 2010 15:34:12 -0700
Jerry Toung <jrytoung@gmail.com> wrote:
> Hello List,
> I am on 8.0 RELEASE amd64. My system has 2 RAID arrays connected to 2
> separate
> controllers.
> My I/O throughput tests jumped by ~100MB/sec on both channels, when I
> commented out the
> following piece of code from kern/vfs_bio.c
>
> void
> waitrunningbufspace(void)
> {
> /*
> mtx_lock(&rbreqlock);
> while (runningbufspace > hirunningspace) {
> ++runningbufreq;
> msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
> }
> mtx_unlock(&rbreqlock);
> */
> }
>
> so far, I can't observe any side effects of not running it. Am I on a time
> bomb?
>
Rather than commenting out the code try setting the sysctl
vfs.hirunningspace to various powers-of-two. Default seems to be
1MB. I just changed it on the command line as a test to 2MB.
You can do this in /etc/sysctl.conf.
--
Gary Jennejohn
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20100714090454.1177b96b>