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AJvYcCXNSrRLItB99eT8dDl5m3BGiK0PBiwj/l2Vr9KeV4VfIYuP6RkwnVzqBe3awkaiDUuOCAEOFYPBXBIYjdYG+vkgdk0= X-Gm-Message-State: AOJu0YyAJ+hq/qFPlqNvFbEOcZzf/lbp9ILl6eErlwaYoT7cD79+9YeR dKDPT9PR551cwOW5Nj/xdG8AdOXMqrwuFnA3yL5wfMnyxdpRazfrCN+1weNqmpYD+xUdZxcxmRj VsG5pNh65930XfdU3EIvI7OHPfOrjGfy7Es9O X-Google-Smtp-Source: AGHT+IE33prC+j4X7W/r4BxN9/hCYWkPb+uYN6QR+91KbcEXuxHRt7COS48f5exLRZfX2quewY025NFwAlRWhfAZ8BU= X-Received: by 2002:a05:600c:b91:b0:412:2fe0:35a1 with SMTP id fl17-20020a05600c0b9100b004122fe035a1mr123288wmb.6.1708062955326; Thu, 15 Feb 2024 21:55:55 -0800 (PST) MIME-Version: 1.0 References: <20240208061825.36640-1-byungchul@sk.com> In-Reply-To: <20240208061825.36640-1-byungchul@sk.com> From: Yu Zhao Date: Fri, 16 Feb 2024 00:55:17 -0500 Message-ID: Subject: Re: [PATCH] mm, vmscan: Don't turn on cache_trim_mode at the highest scan priority To: Byungchul Park Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, kernel_team@skhynix.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: 3zfqi4b3qcwn5ab96jdbzciytctz5zze X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: F400816000D X-Rspam-User: X-HE-Tag: 1708062956-104447 X-HE-Meta: U2FsdGVkX18l9jUlT0bfh8QO/aNMccck8owX0ys1b/1Z+GzMtobtPHMNliidvUeXq6NnjAG0rjQMDjvQROvlwcc02koc9oIapOq1jS16OECfm3VRcNEstEfCV1D1n5mJOCdqayPCi1WsOJLK6wjpi2NLeHs8uvUUradO2Ah/H7zvXnwYzoi14KjqCrd0qtk3D8E5R7cCgdOQfHC8BJHJsoYMAWaUeNPeP0VI66h7QMsWCm93Uz6vXdOrS+AoQuXWZrMas8t63gRlPs2l+kUU4F8RDPGYnz9kSWcxDE9FrEoJrIYkThyLvmpsYVCOfGeVTWnKtnc0LEydF+4o99p3beJ2QnwDUSwONO7+VLacqxiOiddcuFc5L+JumLzUdS6aWwvSpwb/I3J5I8BxYICqJ0+bLAjwWht9kjwesReuKfyIJ6Gcx8aDxIhtdFuKF1oDGNLIMSNN9NImXJtRiJa3f8v+f4eUPVxWwm6ZSO6AMItAV3L3USYoAQewPsIVkU++oTT3UbdBHuhoiju6caJzhgV3BdXH0+yxPlaeNoVJFG88heLlEAI/fO9yunSa0GhoLmFVUTfOxZMwPsBzdVQuOfZQ2j9HQhzRFBImJN4ydH3fB/Znlb0Cpx6D5qnGVx0UY3nAHpCe6Fo9vZwIVlW2whLJlczYqfBR3zVL2ba9fPMSDcdGjPIpBh78n2Pi4DCx9BQoY2XrGM1w7bl3n0XlSMowO5AoMcRv5KLMK4Ibok2AjXy819KJGz1ukFb2KFstlIEDpIDf1L7KFewyuvmHISb1uzCZa96h3DBClMpB7nfbU6PaAci2nuhETCZDAuti9lr3shGFbVqsx/Mh0eIXnn0hoWnCgc9A5WzMc7qn3c4sJ1ZngpuRySjsNAxVc/J7PuHTF6Pd5aDTCtzx24cgazyoA04raJCbx28LvWcCzdoy0ZtSmQlE/ylkxmbKTOSe/KoI26HCJe5EhbWLh1M ER0QEVhZ CGU67x6BaCGuQiLSnjCPQa2zGGfJ9+wzx0YJK8opRmiJLMQBlXpWORTyWulSIoP+fWZ1A+ztkDS4im7UX+g/LtfMqKsO3D6nc8V7Bp9pILVaJ3YN1dcKBDFyqRot++iFCQmuuZuQ9oI//nvsNq4rpTrUxN6F/Xd8Tqkv29xc8OchaIgcdL7rcm/8AWXvHLEV7nNHxZStkQqIcf9zAIBNRHGqdDNyutyjtyfC7SyEDIgajimnim+kPd1CfwSaO3KXFKNzWdk+gZW6Fju2VCn3EC7Dq8olWCncBQjPdA84wrTIWfMSj/wtKeS137rE7H4ZlLehyJ3//ww4dVs0= X-Bogosity: Ham, tests=bogofilter, spamicity=0.005054, 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 Thu, Feb 8, 2024 at 1:18=E2=80=AFAM Byungchul Park wr= ote: > > With cache_trim_mode on, reclaim logic doesn't bother reclaiming anon > pages. However, it should be more careful to turn on the mode because > it's going to prevent anon pages from reclaimed even if there are huge > ammount of anon pages that are very cold so should be reclaimed. Even > worse, that can lead kswapd_failures to be MAX_RECLAIM_RETRIES and stop > until direct reclaim eventually works to resume kswapd. Is a theory or something observed in the real world? If it's the former, would this change risk breaking existing use cases? It's the latter, where are the performance numbers to show what it looks like before and after this patch? > Signed-off-by: Byungchul Park > --- > mm/vmscan.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index bba207f41b14..25b55fdc0d41 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -2268,7 +2268,8 @@ static void prepare_scan_control(pg_data_t *pgdat, = struct scan_control *sc) > * anonymous pages. > */ > file =3D lruvec_page_state(target_lruvec, NR_INACTIVE_FILE); > - if (file >> sc->priority && !(sc->may_deactivate & DEACTIVATE_FIL= E)) > + if (sc->priority !=3D 1 && file >> sc->priority & Why 1? > + !(sc->may_deactivate & DEACTIVATE_FILE)) > sc->cache_trim_mode =3D 1; > else > sc->cache_trim_mode =3D 0;