> On Mon, 25 Feb 2019, Jason Harmening wrote: > > > On 2/25/19 9:46 PM, Bruce Evans wrote: > >> > >> block_size <= PAGE_SIZE is very uncommon for ffs, even on systems with > >> large > >> pages.?? MINBSIZE is 4096 in ffs (except in my version, it is 512).?? The > >> default is 32768 in newfs.?? I consider this excessive and only use it for > >> file systems with many files larger than 1GB, but it is the most common > >> size. > >> It is larger than the large page size of 8192. > > > > I think this is a case of filesystem logical block size vs. media sector > > size, right? Here we're checking the devvp's block size, which I think > > should correspond to the sector size. I'd expect cases of that being > > greater than PAGE_SIZE to be uncommon, in fact geli warns when that is the > > case. I probably should've made that clearer in the commit message. > > Yes, I missed that you are checking devvp. ffs_getpages() also checks > devvp. > > So the bug has nothing to do with file system logical (fragment) or i/o > (block) block size's, except file systems themselves won't work unless > their i/o size is a multiple of the underlying devices (sector) i/o size. > > Are there physical disk with sector size > PAGE_SIZE now?
I have been told that there are some sd/flash devices that have a 16k physical sector size, I have not been able to confirm that information though. > It is easy to > create virtual (md) disks with sector size > PAGE_SIZE, and this may even > be useful for avoiding the related problem of having to access large fs > blocks to do i/o to small md sectors. I think it is best to use PAGE_SIZE > blocks in all layers and sometimes combine these into clusters. > > Bruce -- Rod Grimes rgri...@freebsd.org
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