Re: [REGRESSION] [BISECTED] kswapd high CPU usage

[Minchan Kim <minchan@kernel.org>]

On Tue, Feb 02, 2016 at 03:59:50PM +0200, Kirill A. Shutemov wrote:
> On Mon, Jan 25, 2016 at 04:46:58PM +0000, Hugh Greenberg wrote:
> > Kirill A. Shutemov <kirill <at> shutemov.name> writes:
> > 
> > > 
> > > On Sat, Jan 23, 2016 at 03:57:21PM +0000, Hugh Greenberg wrote:
> > > > Kirill A. Shutemov <kirill <at> shutemov.name> writes:
> > > > > 
> > > > > Could you try to insert 
> > "late_initcall(set_recommended_min_free_kbytes);"
> > > > > back and check if makes any difference.
> > > > > 
> > > > 
> > > > We tested adding late_initcall(set_recommended_min_free_kbytes); 
> > > > back in 4.1.14 and it made a huge difference. We aren't sure if the
> > > > issue is 100% fixed, but it could be. We will keep testing it.
> > > 
> > > It would be nice to have values of min_free_kbytes before and after
> > > set_recommended_min_free_kbytes() in your configuration.
> > > 
> > 
> > Before adding set_recommended_min_free_kbytes: 5391
> > After: 67584
> 
> [ add more people to the thread ]
> 
> The 'before' value look low to me for machine with 2G of RAM.
> 
> In the bugzilla[1], you've mentioned zram. I wounder if we need to
> increase min_free_kbytes when zram is in use as we do for THP.
> 
> [1] https://bugzilla.kernel.org/show_bug.cgi?id=110501

Normally, it's recommended to increate min_free_kbytes when zram is
used for swap because zram should allocate a page in reclaim path
dynamically to keep compressed page.

However, when I read bugzilla's perf profile, I can't find
any zram related things and if there is lack of free memory for
zram page allocation due to changing min_free_kbytes, user will see
below error message.

pr_err("Error allocating memory for compressed page: %u, size=%zu\n"

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>