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charset=us-ascii Content-Disposition: inline In-Reply-To: <20250529111504.89912-1-kundan.kumar@samsung.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: CF5E74000F X-Stat-Signature: a1bafhyum37tqbffiph9fnnd3j59zr17 X-Rspam-User: X-HE-Tag: 1748873950-895601 X-HE-Meta: U2FsdGVkX1/zZcb3Zl+Dbaxs6SUOYz4rJCsmHriJF37sBphVlR5qutW7RuJfMERkIATM+VIHCwTLT0coOpSVxqnBqzbLfKqWyA/STEaN14bw/hfbaE3GO1RRZsKGBGVjhWCFNnKGI4zqhAUJiHa6sPcnX5Fzl6Ro0ALbdpjGOXuD8CDCmgTIV1RixdtM2jkQsu1ZM6QRBWdsSvfTppTKTDBXBxhZj4EHBZEXlMbJpV7N9aTRuN8qV1C/LaAFVqpi0DRg9BE5GJMaluk9LObZfcMwG8okw1OaFxZLjxmHzc39WiAUBTJQO7IDoIIYeMWUytXRWEuSyC42gmBAxNHPBqBYoM96vY18SIYv/wJ+yYfvBUNKY4YAtns2vQSqb634cec6+YkW9X1DqnihPqsmKtmPkgwYKbpZG8VO1AJ+fU3p+6/ohU5OloYHxUkLb7g/Qkc3Vr3oRCvoyyiS+OXA8Z54cqMZntGGJZkXjTylff45E58Nzm1R9FBOm1oVVldKRN09OZpG0Y5vTRQYxkY4aXxUpQ5Sq/uReDvlRmMxwFDtuKTSn7kyt/Xk/0L/+bAR/WXZxV8u2w5NL2rfkEUycsozx/KwOP4oevxeG+3KgoFUVDX6TdxJhg64mwnBlpHxs7QnupmUoUNpynY1x4GkFIIGvnsieqZyp5IUCM4YASV0b8OOxqeq8ipvfZtJdFsapsAKDGoFdZ7xtTpAZulHqJwXCVVrWXyKh6SbSEjaKRNZ5RwCZbwYNcpdfudN3lgh8WqAkjxkoqT3oQzWOqX5ckkB9VUuTa0VvsCUNSDblnF3V/WXOFuIUn8GmYHkv2uNkkBUCnZXx85AGXgxV+TbJXXFhQccDgil/+jlCVhk9V65LOgiY+icWA== 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 Thu, May 29, 2025 at 04:44:51PM +0530, Kundan Kumar wrote: > Number of writeback contexts > =========================== > The plan is to keep the nr_wb_ctx as 1, ensuring default single threaded > behavior. However, we set the number of writeback contexts equal to > number of CPUs in the current version. Later we will make it configurable > using a mount option, allowing filesystems to choose the optimal number > of writeback contexts. Well, the proper thing would be to figure out a good default and not just keep things as-is, no? > IOPS and throughput > =================== > We see significant improvement in IOPS across several filesystem on both > PMEM and NVMe devices. > > Performance gains: > - On PMEM: > Base XFS : 544 MiB/s > Parallel Writeback XFS : 1015 MiB/s (+86%) > Base EXT4 : 536 MiB/s > Parallel Writeback EXT4 : 1047 MiB/s (+95%) > > - On NVMe: > Base XFS : 651 MiB/s > Parallel Writeback XFS : 808 MiB/s (+24%) > Base EXT4 : 494 MiB/s > Parallel Writeback EXT4 : 797 MiB/s (+61%) What worksload was this? How many CPU cores did the system have, how many AGs/BGs did the file systems have? What SSD/Pmem was this? Did this change the write amp as measure by the media writes on the NVMe SSD? Also I'd be really curious to see numbers on hard drives. > We also see that there is no increase in filesystem fragmentation > # of extents: > - On XFS (on PMEM): > Base XFS : 1964 > Parallel Writeback XFS : 1384 > > - On EXT4 (on PMEM): > Base EXT4 : 21 > Parallel Writeback EXT4 : 11 How were the number of extents counts given that they look so wildly different?