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charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Stat-Signature: ta6hm9reag6t51sthixuz1tsgy7tbdgm X-Rspamd-Queue-Id: 0F8541A0010 X-Rspamd-Server: rspam03 X-HE-Tag: 1773703579-997357 X-HE-Meta: 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 6iW82r15 A2HzRHUKkuuqWJQIWN0GfQ1lOjqYa8HDyESMXXzwj4ZiEQns3cmkROynHzez2LWsMGmV7GHUZluU3BoxMHJk4Whq8pEqNzTJ/A3V2O5HY2M7UE/vlQSP87sRzy4tiZXMrP96ivgDJBvdPoS529MSn9bLTpIJgTT3h8n/NkWZFBlEVF990wd1W6wAnAlCcSt97s5iybbdhg/UlbxnBIMT7KVW/TYTwO3sEqONk8hvLU1MrrkaYetMF3Onw7ekzZsFOtUlIhXy9lV8CJSpNeArNGcTfnQ/Lj30UbxIgziNroWJXDxoFu8mFwZaNTHCqJbc7G5++H/jcZzEbpngUihTM4xmg75efGEjgUZfj0i7+0/Esw5fMItC4CnT1mA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2/19/26 6:53 AM, Bart Van Assche wrote: > On 2/19/26 1:54 AM, Hannes Reinecke wrote: >> I (together with the Czech Technical University) did some experiments=20 >> trying to measure memory fragmentation with large block sizes. >> Testbed used was an nvme setup talking to a nvmet storage over >> the network. >> >> Doing so raised some challenges: >> >> - How do you _generate_ memory fragmentation? The MM subsystem is >> =C2=A0=C2=A0 precisely geared up to avoid it, so you would need to com= e up >> =C2=A0=C2=A0 with some idea how to defeat it. With the help from Willy= I managed >> =C2=A0=C2=A0 to come up with something, but I really would like to dis= cuss >> =C2=A0=C2=A0 what would be the best option here. >> - What is acceptable memory fragmentation? Are we good enough if the >> =C2=A0=C2=A0 measured fragmentation does not grow during the test runs= ? >> - Do we have better visibility into memory fragmentation other than >> =C2=A0=C2=A0 just reading /proc/buddyinfo? >=20 > The larger the block size, the higher the write amplification (WAF), > isn't it? Why to increase the block size since there is a solution > available that doesn't increase WAF, namely zoned storage? (replying to my own email) The following paper shows that it is possible to achieve great performance with filesystems like ext4 and ZNS SSDs by implementing an FTL in software (ZTL). This could be a more interesting approach than optimizing host software for large indirection units. See also Sass, Jan, Andr=C3=A9 Brinkmann, Matias Bj=C3=B8rling, Xubin He, and Reza Salkhordeh. "ZTL: A block layer ZNS driver." Journal of Systems Architecture (2026): 103757. (https://www.sciencedirect.com/science/article/pii/S1383762126000755). Bart.