From: Andrew Morton <akpm@linux-foundation.org>
To: " Christian König " <ckoenig.leichtzumerken@gmail.com>
Cc: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
linux-mm@kvack.org, ray.huang@amd.com, vbabka@suse.cz
Subject: Re: [PATCH 2/2] drm/ttm: optimize the pool shrinker a bit v2
Date: Thu, 15 Apr 2021 13:33:10 -0700 [thread overview]
Message-ID: <20210415133310.1ee9df70a9eb887be937c3a3@linux-foundation.org> (raw)
In-Reply-To: <20210415115624.2904-2-christian.koenig@amd.com>
On Thu, 15 Apr 2021 13:56:24 +0200 "Christian König" <ckoenig.leichtzumerken@gmail.com> wrote:
> @@ -530,6 +525,11 @@ void ttm_pool_fini(struct ttm_pool *pool)
> for (j = 0; j < MAX_ORDER; ++j)
> ttm_pool_type_fini(&pool->caching[i].orders[j]);
> }
> +
> + /* We removed the pool types from the LRU, but we need to also make sure
> + * that no shrinker is concurrently freeing pages from the pool.
> + */
> + sync_shrinkers();
It isn't immediately clear to me how this works. ttm_pool_fini() has
already freed all the pages hasn't it? So why would it care if some
shrinkers are still playing with the pages?
Or is it the case that ttm_pool_fini() is assuming that there will be
some further action against these pages, which requires that shrinkers
no longer be accessing the pages and which further assumes that future
shrinker invocations will not be able to look up these pages?
IOW, a bit more explanation about the dynamics here would help!
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next prev parent reply other threads:[~2021-04-15 20:33 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-15 11:56 [PATCH 1/2] mm/vmscan: add sync_shrinkers function Christian König
2021-04-15 11:56 ` [PATCH 2/2] drm/ttm: optimize the pool shrinker a bit v2 Christian König
2021-04-15 14:33 ` Huang Rui
2021-04-15 20:33 ` Andrew Morton [this message]
2021-04-16 7:08 ` Christian König
2021-04-26 11:15 ` Christian König
2021-04-15 13:23 ` [PATCH 1/2] mm/vmscan: add sync_shrinkers function Daniel Vetter
2021-08-20 12:05 Adding sync_shrinkers function for TTM pool optimization Christian König
2021-08-20 12:05 ` [PATCH 2/2] drm/ttm: optimize the pool shrinker a bit v2 Christian König
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