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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Mon, 20 Sep 2021 16:29:52 -0700
Message-ID: <CAHk-=wh2_yEuAC5=9VWefK+0JD9pAKf8qL-vpSmS7MtLA8SZEA@mail.gmail.com>
Subject: Re: [PATCH v3] mm: fs: invalidate bh_lrus for only cold path
To:     Minchan Kim <minchan@kernel.org>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Laura Abbott <labbott@kernel.org>,
        Oliver Sang <oliver.sang@intel.com>,
        David Hildenbrand <david@redhat.com>,
        John Dias <joaodias@google.com>,
        Matthew Wilcox <willy@infradead.org>,
        Michal Hocko <mhocko@suse.com>,
        Suren Baghdasaryan <surenb@google.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-mm <linux-mm@kvack.org>, lkp@lists.01.org,
        kernel test robot <lkp@intel.com>,
        "Huang, Ying" <ying.huang@intel.com>,
        Feng Tang <feng.tang@intel.com>, zhengjun.xing@intel.com,
        Chris Goldsworthy <cgoldswo@codeaurora.org>
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On Tue, Sep 7, 2021 at 2:24 PM Minchan Kim <minchan@kernel.org> wrote:
>
> kernel test robot reported the regression of fio.write_iops[1]
> with [2].
>
> Since lru_add_drain is called frequently, invalidate bh_lrus
> there could increase bh_lrus cache miss ratio, which needs
> more IO in the end.
>
> This patch moves the bh_lrus invalidation from the hot path(
> e.g., zap_page_range, pagevec_release) to cold path(i.e.,
> lru_add_drain_all, lru_cache_disable).

Was this confirmed to fix the regression?

I only see the "tested with 5.14" that the regression was still there

   https://lore.kernel.org/lkml/034fc860-d0d0-0c61-09d2-3c41c4f020c6@intel.com/

I don't see a confirmation that this patch fixed it.

It looks likely, but if you have the confirmation somewhere, it would
help to link that too.

Or did I miss it?

           Linus