Re: cp(1) of large files is causing 100% CPU utilization and poor transfer

On Sat, Jan 2, 2021 at 9:12 AM Matthias Apitz <guru_at_unixarea.de> wrote:

> El día sábado, enero 02, 2021 a las 09:06:24a. m. -0700, Alan Somers
> escribió:
>
> > > As I said, it can be reproduced using only the local file system. This
> > > was setup recently on a SSD:
> > >
> > > # dmesg | grep ada0
> > > ada0 at ahcich0 bus 0 scbus0 target 0 lun 0
> > > ada0: <TS512GMTS430S R0906A> ACS-2 ATA SATA 3.x device
> > > ada0: Serial Number F995890846
> > > ada0: 600.000MB/s transfers (SATA 3.x, UDMA6, PIO 1024bytes)
> > > ada0: Command Queueing enabled
> > > ada0: 488386MB (1000215216 512 byte sectors)
> > >
> > > and by this procedure:
> > >
> > > # gpart create -s gpt ada0
> > > # gpart add -t freebsd-boot -s 512k -a4k -l ssdboot ada0
> > > # gpart bootcode -b /boot/pmbr -p /boot/gptboot -i1 ada0
> > > # gpart add -t freebsd-ufs -l ssdrootfs -b 1m -s 2g ada0
> > > # gpart add -t freebsd-ufs -l ssdvarfs -a 1m -s 2g ada0
> > > # gpart add -t freebsd-ufs -l ssdusrfs -a 1m ada0
> > > # newfs -U -t /dev/gpt/ssdrootfs
> > > # newfs -U -t /dev/gpt/ssdvarfs
> > > # newfs -U -t /dev/gpt/ssdusrfs
> > >
> > > # gpart show -l ada0
> > > =>        40  1000215136  ada0  GPT  (477G)
> > >           40        1024     1  ssdboot  (512K)
> > >         1064         984        - free -  (492K)
> > >         2048     4194304     2  ssdrootfs  (2.0G)
> > >      4196352     4194304     3  ssdvarfs  (2.0G)
> > >      8390656    16777216     4  ssdswap  (8.0G)
> > >     25167872   975046656     5  ssdusrfs  (465G)
> > >   1000214528         648        - free -  (324K)
> > >
> > > # mount -t ufs
> > > /dev/gpt/ssdrootfs on / (ufs, local, soft-updates)
> > > /dev/gpt/ssdvarfs on /var (ufs, local, soft-updates)
> > > /dev/gpt/ssdusrfs on /usr (ufs, local, soft-updates)
> > >
> > > When I run in the /usr fs the command
> > >
> > > # cp -p guru-20210102.tar.gz xxx
> > >
> > > it copies around 168M per minute.
> > >
>
> > Is that copying from /usr to /usr, or from /usr to /var or /?
>
> # cd /home/backups
> # cp -p guru-20210102.tar.gz xxx
>
> i.e. from /usr to /usr.
>
>         matthias
>

Ok, let's narrow this down.  Could you please run the command with the
attached D script ?
sudo dtrace -s copy_file_range.d -c "cp -p guru-20210102.tar.gz xxx"