svn commit: r351673 - in head: lib/libmemstat share/man/man9 sys/cddl/compat/opensolaris/kern sys/kern sys/vm

[Slawa Olhovchenkov]

On Sat, Sep 07, 2019 at 10:50:34AM -0400, Mark Johnston wrote:

> On Wed, Sep 04, 2019 at 05:45:24PM +0300, Slawa Olhovchenkov wrote:
> > On Tue, Sep 03, 2019 at 06:01:06PM -0400, Mark Johnston wrote:
> > > > Mostly problem I am see at this
> > > > work -- very slowly vm_page_free(). May be currenly this is more
> > > > speedy...
> > > 
> > > How did you determine this?
> > 
> > This is you guess:
> 
> So was the guess correct?

I am just trust to you.
How to check this guess?

> If so, IMO the real solution is to avoid kmem_*
> for data buffers and use ABD instead.

What problem resolve this?
ABD any way is slowly vs kmem_*.

> > ======
> > >         while ((slab = SLIST_FIRST(&freeslabs)) != NULL) {
> > >                 SLIST_REMOVE(&freeslabs, slab, uma_slab, us_hlink);
> > >                 keg_free_slab(keg, slab, keg->uk_ipers);
> > >         }
> > > 2019 Feb  2 19:49:54.800524364       zio_data_buf_1048576  1032605 cache_reclaim limit      100 dom 0 nitems     1672 imin      298
> > > 2019 Feb  2 19:49:54.800524364       zio_data_buf_1048576  1033736 cache_reclaim recla      149 dom 0 nitems     1672 imin      298
> > > 2019 Feb  2 19:49:54.802524468       zio_data_buf_1048576  3119710 cache_reclaim limit      100 dom 1 nitems        1 imin        0
> > > 2019 Feb  2 19:49:54.802524468       zio_data_buf_1048576  3127550 keg_drain2
> > > 2019 Feb  2 19:49:54.803524487       zio_data_buf_1048576  4444219 keg_drain3
> > > 2019 Feb  2 19:49:54.838524634       zio_data_buf_1048576 39553705 keg_drain4
> > > 2019 Feb  2 19:49:54.838524634       zio_data_buf_1048576 39565323 zone_reclaim:return
> > >
> > > 35109.486 ms for last loop, 149 items to freed.
> > 
> > 35ms to free 149MB (38144 4KB pages), so roughly 1us per page.  That
> > does seem like a lot, but freeing a page (vm_page_free(m)) is much
> > more expensive than freeing an item to UMA (i.e., uma_zfree()).
> > Most of that time will be spent in _kmem_unback().
> > ======