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Thu, 15 Oct 2026 07:46:03 -0700 (PDT) Received: from [10.131.15.42] ([115.200.102.144]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-cd635cdffa5sm1393286a12.29.2026.10.15.07.45.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 15 Oct 2026 07:46:02 -0700 (PDT) From: Aveline Noir To: SJ Park Cc: Andrew Morton , damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [BUG] DAMON_STAT: idle percentiles out of order on 32-bit In-Reply-To: <20261015141319.88393-1-sj@kernel.org> References: <20261015141319.88393-1-sj@kernel.org> Date: Thu, 15 Oct 2026 22:45:01 +0800 Message-ID: <179207550140.2.6042983090152523193@gmail.com> X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: AA80116000A X-Rspam-User: X-Stat-Signature: r5eb99diwh81oxatfuezmf4e9a3ehtkn X-HE-Tag: 1792075564-579906 X-HE-Meta: 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 HaX3e8Yk 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi SJ, I haven't seen this affect a real workload. I found it while testing DAMON_STAT on 32-bit. The upper percentiles can stay at zero or keep old values. If someone uses them to judge how much memory is cold or to choose a reclaim threshold, they could get the wrong picture. I'll send the fix and test results in a separate mail. Thanks, Aveline Noir