From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id D4C7CC41535 for ; Wed, 20 Dec 2023 00:00:38 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 445058D0002; Tue, 19 Dec 2023 19:00:38 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 3F4658D0001; Tue, 19 Dec 2023 19:00:38 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2BBF58D0002; Tue, 19 Dec 2023 19:00:38 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 1A0268D0001 for ; Tue, 19 Dec 2023 19:00:38 -0500 (EST) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id DCBFDC0446 for ; Wed, 20 Dec 2023 00:00:37 +0000 (UTC) X-FDA: 81585240114.01.826C33B Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by imf15.hostedemail.com (Postfix) with ESMTP id 0B02CA0019 for ; Wed, 20 Dec 2023 00:00:35 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=wYJFDCvY; spf=pass (imf15.hostedemail.com: domain of akpm@linux-foundation.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1703030436; a=rsa-sha256; cv=none; b=OgB6TGK2MtXTnyCWwV52y8q+lEwmB4IR0v3BNgA7k+7LsyK7t7T7805Yf+fdIJitloF9jD RVQI6+XiFQYjBQgPnoUZrZNU8WHfUEExeXy23csWLrE9O8sAhy5lvZmnlpZzD8U6Jhy8Bm q2PORS/PA/aQ9CPmcEu2RK8HwRzIIKc= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=wYJFDCvY; spf=pass (imf15.hostedemail.com: domain of akpm@linux-foundation.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1703030436; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=tQUMkEIQnj8DHnCHbUmBlYIE2wpmUM2XjvCxeBHFquM=; b=DGngfPzNkaLt44Bf75efEbyLmhz+MwYwqNimkhMAYQXQuXttU8JekwvNU9C44umtu1z888 AEwxxQHVyXOIGxPZRJwJWIzsWhSqQhAHN4gdvztWFgzXUBP0pcw9V5iqIJucXHylAlw6IU Nr9nLh9uRC8XYWlRGFZnWIhCy0OYkL8= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by ams.source.kernel.org (Postfix) with ESMTP id 7A4B4B81823; Wed, 20 Dec 2023 00:00:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AE7A3C433C8; Wed, 20 Dec 2023 00:00:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1703030433; bh=z3SjaW2R9iirc95FIVnm67CZ6xeYFdVK5wrrF3Oe5MY=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=wYJFDCvYMrbSUiV3LoIvN5VlyCngkY964JQ5n4wg+APy3h1mGAX21yKBzl/MKT3OH 8WrsLLKdEavJk0ixfOY2BZVAG9uxn9nthUxITiyeG5zosyT7ZW0O/DshJOdxjJRdnG b/AeSCDJqLJoUhr3YMduwZBfJbiY+vph/VkxEAwg= Date: Tue, 19 Dec 2023 16:00:33 -0800 From: Andrew Morton To: Kevin Hao Cc: linux-mm@kvack.org, "Rafael J. Wysocki" , Pavel Machek Subject: Re: [PATCH v2] mm/khugepaged: Remove redundant try_to_freeze() Message-Id: <20231219160033.35263ae2818c3e8bd73ae086@linux-foundation.org> In-Reply-To: <20231219231753.683171-1-haokexin@gmail.com> References: <20231219231753.683171-1-haokexin@gmail.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 0B02CA0019 X-Stat-Signature: djor3cdpkca38qwxpkzztsknkfxttx1j X-Rspam-User: X-HE-Tag: 1703030435-370067 X-HE-Meta: U2FsdGVkX1/QrHu7e8ELcgfikgxJsKkPUhp6pCeBars/QuQxUtr4uYGrtuGTc8rrqP8Tg+crE/N4+5fUPwhBcWoG6tI0C1rUkUlM8ZwW8nylGB0Wm76sYUpEnYWkIbhZLpCjjzGnZXguhLoeo1kCY7JwfZfNf52iJ2UzJfd6ttv3wAsyb8U72aoKiL5/EHROgS6o0LvZFRg6apNLzB/b3NqBNGaw4fdZOfclb0Gl9Gh5d4G0HujGSDultkkA0hWdUMLGaKDS9nJCE7J7CjSs4BcvFBRZn2zHfKcKpk+ifiqnJ8quGfNjO6IJieB19swl8hU7MdUpePADn9RutUm9XaIbpPl6U/GQo2+Z0AF+K08YrkZIq4QyqxKLrrktQS0xqu46ZVedVBIZXPZw2Qx63FsOLyZy4NGa9rIu5ZxIeO9JeihkLveZV0OXMSQAiPnBCQIkUgTcJp4V7dclEgGcP0pWn4dGAQTojBxF8jgBrHCcPaGm/VWaBhFM9KD7Fx7Gsg8arG42oHFqSKpdfmzLhKAoOtvSecTpWq3obYYEWVd+hPFtB98tKEMCnLfMnLwaO5Gva8cjtO2qyih4uJA4M1/lzXIgH/lAg6TFvW2X23meaDnF2+TBDWlz9Tszx44CazDYn//z2h692C7pv7DbChLD9XTy8BfTufrEj8bplGtSsW8eKb3HmNohin31vjanNbJC9Gh9hMvOCgnNSMz6SkeEx4b6o2ZvJLTrG9G4NBwdunnLEhn5pFn/f8GxcRTSxB73T27zt52AMAzsGZiKTW04cxgjeTkuvGUjM749fQpNNkERFiLXcgQy/fRd+5ws0cysaty/QRhv2pmzmR4fQzHRKLFD2jHHjLFNHA82rRrNMJC4NzCzRZPCjwLGjnBaGcfMG0wu1OG8GO3dYbTh7V8sAfbV0uYS7Nhs9AAcCi/3wUe/hG2kwN8PHne6baLFJ9Q9jfdSatxgHjGuX5q upWxd11j kRmpnggXD6c2jq0gKVnxUHpbTO3KBsuQ/lQWMrJHP4YUEYlZxdr7L73m9l8i+hsxcP9SiNXC6uuTERuKLt3x28/tdzRXXLCTdxCwhodr8gz/fIL94jiHtLSmgLe+nYjs+xAdheZslktUAfhbVBL5SbYDQ3n2F6TNQLmviuR6LEdo1ENdD1cF2zwCZnX2vvJBoyeyW6F5OMnffpJ+XpEjkUCNHNIXbEt1lYJfMdlGcJ5HPLBeBLdGPd8qb/f8PmzFYeEOV6kp2ImZbwT3uyph+GBibPIx9BaGSROZdMWTqd1N5egs= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 20 Dec 2023 07:17:53 +0800 Kevin Hao wrote: > A freezable kernel thread can enter frozen state during freezing by > either calling try_to_freeze() or using wait_event_freezable() and its > variants. However, there is no need to use both methods simultaneously. > The freezable wait variants have been used in khugepaged_wait_work() > and khugepaged_alloc_sleep(), so remove this redundant > try_to_freeze(). > > ... > > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -2500,7 +2500,7 @@ static void khugepaged_do_scan(struct collapse_control *cc) > while (true) { > cond_resched(); > > - if (unlikely(kthread_should_stop() || try_to_freeze())) > + if (unlikely(kthread_should_stop())) > break; > > spin_lock(&khugepaged_mm_lock); What are the effects upon worst-case freezing latency?