svn commit: r343030 - in head/sys: cam conf dev/md dev/nvme fs/fuse fs/nfsclient fs/smbfs kern sys ufs/ffs vm

[Justin Hibbits]

On Thu, 14 Feb 2019 15:34:10 -0800
Gleb Smirnoff <glebius at freebsd.org> wrote:

>   Hi Justin,
> 
> On Wed, Feb 13, 2019 at 07:24:50PM -0600, Justin Hibbits wrote:
> J> This seems to break 32-bit platforms, or at least 32-bit book-e
> J> powerpc, which has a limited KVA space (~500MB).  It preallocates
> J> I've seen over 2500 pbufs, at 128kB each, eating up over 300MB KVA,
> J> leaving very little left for the rest of runtime.
> J> 
> J> I spent a couple hours earlier today debugging with Mark Johnston,
> J> and his consensus is that the vnode_pbuf_zone is too big on 32-bit
> J> platforms.  Unfortunately I know very little about this area, so
> J> can't provide much extra insight, but can readily reproduce the
> J> issues I see triggered by this change, so am willing to help where
> J> I can.  
> 
> Ok, let's roll back to old default on 32-bit platforms and somewhat
> reduce the default on 64-bits.
> 
> Can you please confirm that the patch attached works for you?
> 

Hi Gleb,

Thanks for the patch.  I've built and installed.  My machine boots up
fine, and I dropped to ddb to check vmem.  Results are as follows:

r343029:
  kernel arena domain:
    size: 67108864
    inuse: 66482176
    free: 62668

  kernel arena:
    size: 624951296
    inuse: 579207168
    free: 45744128

r344123 with your patch:
  kernel arena domain:
    size: 71303168
    inuse: 68153344
    free: 3149824
  kernel arena:
    645922816
    inuse: 632369152
    free: 13553664

I've kicked off a buildworld+buildkernel to see how it survives.

This machine has 8GB RAM and 4GB swap, if that has any impact.

- Justin