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AJvYcCWh0Wuk0MgCh2uY+ZLs1gI7qDPpbLAt80A3D3N8y3UOqqxk7zKLLm0ABgo7dk9PnBOq+4e3BzZIWFVnFSO3imlgm30= X-Gm-Message-State: AOJu0Yx9jQNs5A/jxMy/j2D+KKEPneNDjbwia3m5AZZnOsIWUOmdFjbj g6RSZlIi1oxNwGRtrdapLRiGPRQdHWlgYIMhIGvuQfPmZdD+8Ps5nqxiJN5OhYCIMsKlzOQnGFj pNbjhD+WuWL+7pQsDOK886gMA686AXjoKU0B8 X-Google-Smtp-Source: AGHT+IEWYnD8zi9B/9e6rsEEFUT2DDvElQ2Eudhj+kVTkeneK2S5lMccsus0ay4fQqoaWUv3I46OXolsus2IOHEtW58= X-Received: by 2002:ac8:5889:0:b0:447:d555:7035 with SMTP id d75a77b69052e-451bb9c7f0cmr451931cf.13.1722887509768; Mon, 05 Aug 2024 12:51:49 -0700 (PDT) MIME-Version: 1.0 References: <20240730125346.1580150-1-usamaarif642@gmail.com> In-Reply-To: From: Yu Zhao Date: Mon, 5 Aug 2024 13:51:11 -0600 Message-ID: Subject: Re: [PATCH 0/6] mm: split underutilized THPs To: Rik van Riel Cc: David Hildenbrand , Usama Arif , akpm@linux-foundation.org, linux-mm@kvack.org, hannes@cmpxchg.org, shakeel.butt@linux.dev, roman.gushchin@linux.dev, baohua@kernel.org, ryan.roberts@arm.com, rppt@kernel.org, willy@infradead.org, cerasuolodomenico@gmail.com, corbet@lwn.net, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, kernel-team@meta.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: D040880007 X-Stat-Signature: pznaqhox6icnmfmggh5n1s7mauci6w4b X-HE-Tag: 1722887510-390809 X-HE-Meta: U2FsdGVkX1/u365/G58/wGhBRXzRHVw0Rjpx9P/T0v77kmmHBMnIEDNhd9aGIEvgIWe5HwuEp9r/aI96IY6H7nOlGPMJoTMhgAG6SOW84+Ku6Khk7U8MHXUbnUSG2hIk4zvhJTvTZ/mBKlIbau1xSEZFchBM/Uiqk4W9hNTPfSHySxBTz1gBwyW3IQ+kvZIyDHyd0uKLLP6+ItYWwV/S85SzaXQLTpZuwothLW9F9mWHuh35HRwvb3rOs2q8U4espOmgtzULKEtqRS0eVW++Arz7sTQ3u3rK2fH2mpY8JtnUn5fIKEPciCvLl99yF2SagGqcyldqe6mMebUUWwb+iKPBMzZCXJLqdEaKUeOtFybhfeJA0KOFBH8zuchJoESyZZZnw4yRAo53n3A/EzKF3IZd4AvabfdlLckQFogXiPPzD16c7mqSkGAUPhFQjnI2svkW5+Wl/X1jPo8rlKH9gYDTvWQ0vmZiRmfn76Uix9EA7UXz/oFh+7UVqPtGmqEBcIHtDU/W8gWoVWqMe3+E9+c6yRpfTRdhPl+DIbyFTfUAjqgb9IgQITls4IsoT/FsKAAGM54qlCCbmsmHQSm4Ca2Ab3vQjXVceIEOFiWwK4ku9bxL8vsxizXw8irb+WTIKkRK1kmhPwTDNAgX8eee6CFnjIgFOVj8uQUxX3uYttuYWYDSSLshnXQK/7XnRqx1NfPy3OW60Mh0lS3krLbVQOplnXmPIQ2cclKK7QGleG6WB1lDXqoNUJ/TT9TRJCkSUmFrxA0tkc/0RIVDymVTMa4D/bogFUALigJv0ZRe8nXvto4O3jNQQ5+f4b92Dglkq2hX+2Lmi3sZHjGGMZ6RJp3L6H9DPRDD60kYhi1d8L+zCB/WAsS7OomV2lWn1FCBZX4kJOnFwDE5JwsN7LWcLeHqCXjlvR/lOqhJmidKftuMsvxZ6bCr64vhz7CD46z7ACTP4ulzZUpTqzc1FDE 91LWPr80 vBMxi3Q3yEF5R+35JGvliqziXAX0ZhNj9ySdg3yiWAUuvEE+gHElPaN1ZkUIGYVc3LOgMpnxLhs5I95kfZXNGx9ubQ6Lk6kIIS01UW3BQzN2pB45nF2SMQgWE9xlmy+jE+XyVrPOG5A61BIAVW5SII0Z/efKWElwiZrcQ8sBafYjTzzQd1Y1WqFPMhTFH0aRia1sluc1Fj89NHa28QXjqfLvPnIR0AfWiRYVLHYU5omT3quJOJccdW/0bhUiuo1nw+YaQIntuP1F3BHXkgLirU/CHT0pf0npnY47kG4OJMiGJ5jmGb/GKlWsFkMtzQYU+Uh3kvCOuLj/xFa1xDDto6PzTWQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000021, 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 Sun, Aug 4, 2024 at 7:33=E2=80=AFPM Rik van Riel wrot= e: > > On Sun, 2024-08-04 at 15:54 -0600, Yu Zhao wrote: > > On Thu, Aug 1, 2024 at 9:47=E2=80=AFAM David Hildenbrand > > wrote: > > > > > > On 01.08.24 08:09, Yu Zhao wrote: > > > > > > > > I would recommend shatter [1] instead of splitting so that > > > > 1) whoever underutilized their THPs get punished for the > > > > overhead; > > > > 2) underutilized THPs are kept intact and can be reused by > > > > others. > > > > > > > > [1] > > > > https://lore.kernel.org/20240229183436.4110845-3-yuzhao@google.com/ > > > > > > > > > > Do you have any plans to upstream the shattering also during > > > "ordinary" > > > deferred splitting? > > > > Yes, once we finish verifying it in our production. > > > > Shattering does seem like a nice improvement to the THP shrinker! > > However, given that the shattering code is still being verified, > and the THP shrinker policy will no doubt need some tuning once > more real world workloads get thrown at it, would it make sense > to do those two things in parallel? > > We could move forward with the THP shrinker as-is today, and use > the increased exposure it gets to fine tune the shrinking policy, > and then move it over to using the shattering code once that is > ready. > > Is there any good reason to serialize these two things? I'm fine with whichever way you prefer: if you are eager to try shattering in your production environment, I'd be incentivized to throw in extra engineers and get it ready for you asap.