I'm not sure what it takes to make the raid code fully multithreaded, but it should help on this occation. Perhaps it would be sufficient to move the interrupts to a single socket, but I think he tried that - I was asking him because of the load of CPU interconnects and the lower bandwidth compared to main memory. Still, a RAID controller has a slower CPU and less memory bandwidth, so it really should be slower, but isn't. I'm not quite sure why this is the case. Vennlig hilsen roy -- Roy Sigurd Karlsbakk (+47) 98013356 http://blogg.karlsbakk.net/ GPG Public key: http://karlsbakk.net/roysigurdkarlsbakk.pubkey.txt -- Hið góða skaltu í stein höggva, hið illa í snjó rita. ----- Original Message ----- > From: "Roger Heflin" <rogerheflin@xxxxxxxxx> > To: "Roy Sigurd Karlsbakk" <roy@xxxxxxxxxxxxx> > Cc: "Jean De Gyns" <Jean.DeGyns@xxxxxxxxxx>, "Song Liu" <liu.song.a23@xxxxxxxxx>, "Wilson Jonathan" > <i400sjon@xxxxxxxxx>, "Linux Raid" <linux-raid@xxxxxxxxxxxxxxx> > Sent: Wednesday, 20 February, 2019 01:26:07 > Subject: Re: RAID6 : Sequential Write Performance > One though I have is if you can figure out which core is being maxed > out then turn off its hyperthread. On the single cpu speed benchmarks > I have ran turning off the shared idle hyperthread gains several % on > cpu bound benchmarks. If the hyperthread is being actively used by > some other process then it should gain quite a bit more. You may also > want to run turbostat and verify that the processor in question is > running full speed and/or turboboosting (it probably is if everything > is working right). > > On Tue, Feb 19, 2019 at 5:33 PM Roy Sigurd Karlsbakk <roy@xxxxxxxxxxxxx> wrote: >> >> > Is this process going to be running all of the time, or just run for a >> > few minutes/hours at a time? If for a few minutes at a time you may >> > want to use a raid0 ssd array for the data collection and then have >> > another process to move that data onto the raid6. If the data is >> > split multiple files (a few gb each) then the backend process can move >> > the finished files just behind the main process and if the files are >> > small enough then they will still be in file cache and you won't have >> > to read off of the ssd array, and you will be isolated from random >> > blips on the spinning disks. Give you are talking about 12 disks, if >> > one of those spinning disk blips it will be whatever timeout you set >> > on the disk assuming you have a disk that allows the timeout to be set >> > (the lowest I have found for that timeout is 0.1seconds). >> >> He did use SSDs to check this, with RAID-6, and the performance issue was the >> same, CPU-bound >> >> Vennlig hilsen >> >> roy >> -- >> Roy Sigurd Karlsbakk >> (+47) 98013356 >> http://blogg.karlsbakk.net/ >> GPG Public key: http://karlsbakk.net/roysigurdkarlsbakk.pubkey.txt >> -- >> Hið góða skaltu í stein höggva, hið illa í snjó rita.
