Date: Fri, 4 Mar 2022 20:11:20 -0500 From: mike tancsa <mike@sentex.net> To: Karl Denninger <karl@denninger.net>, freebsd-fs@freebsd.org Subject: Re: md disks EXTREMELY slow 12.3-STABLE Message-ID: <bdc83a45-4bed-d896-0709-e8253bded1bb@sentex.net> In-Reply-To: <8eb0baaa-f22b-57f7-6b6f-6d93ddb2dee5@denninger.net> References: <97013161-b119-4c98-a294-c733ca000a34@denninger.net> <e775b9ba-d506-8189-ab18-c8bc4f384c42@gmx.at> <8eb0baaa-f22b-57f7-6b6f-6d93ddb2dee5@denninger.net>
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On 3/4/2022 3:06 PM, Karl Denninger wrote: > On 3/4/2022 14:34, infoomatic wrote: >> On 04.03.22 17:22, Karl Denninger wrote: >>> Load average is 0.3 yet the md0 drive is pinned at 100% busy with just >>> 50 transactions-per-second! >> >> you mean md(4), the memory disk, right? ... just to be sure it is no >> typo >> > Correct. > > I think I've found the issue -- The "-13" build is using a vnode on > the spinning rust ZFS pool (albeit a fairly high-performance one > comprised of mirrored vdevs) for backing store. I'm not sure WHY this > winds up being so insanely slow, but it does. I'm going to move it > either to memory/swap (since I have a bunch) or stick it on the SSD > pool since creating an md in RAM is, as expected, ridiculously fast. > /Try doing mount -o async. It makes a big difference speed wise for writes. / / ---Mike/
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