Date: Sat, 7 Sep 2019 18:31:10 +0300 From: Slawa Olhovchenkov <slw@zxy.spb.ru> To: Mark Johnston <markj@freebsd.org> Cc: Andriy Gapon <avg@freebsd.org>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r351673 - in head: lib/libmemstat share/man/man9 sys/cddl/compat/opensolaris/kern sys/kern sys/vm Message-ID: <20190907153110.GG3953@zxy.spb.ru> In-Reply-To: <20190907145034.GB6523@spy> References: <201909012222.x81MMh0F022462@repo.freebsd.org> <79c74018-1329-ee69-3480-e2f99821fa93@FreeBSD.org> <20190903161427.GA38096@zxy.spb.ru> <20190903220106.GB26733@raichu> <20190904144524.GD3953@zxy.spb.ru> <20190907145034.GB6523@spy>
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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().
> > ======
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