On Sun, 2019-02-17 at 02:58 +1100, Bruce Evans wrote: > Slowness is relative. In FreeBSD-1, floppy disk devices were still in > use and were especially slow. Now hard disks are slow relative to fast > SSDs. But the number of buffers was unchanged. It is still essentially > unchanged except for vn pager pbufs. The hard disks can complete 128 > i/o's for a full queue much faster than a floppy disk, so the relative > slowness might be similar, but now there are more subsystems and some > systems have many more disks.
The modern replacement for a floppy disk in this regard is an sdcard. When doing large numbers of random writes, such as untarring a snapshot of rootfs to a ufs filesystem on sdcard, gstat will show ms/w values anywhere from 30,000 to 90,000 depending on the card. It stays that way throughout the operation, and IO to all other disks on the system essentially comes to a standstill. This is true whether the card is in a native sdhci controller or a usb-attached multiformat reader/burner. -- Ian _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
