On 11/15/24 12:09, Christoph Hellwig wrote:
On Fri, Nov 15, 2024 at 03:05:21PM +0100, Mikulas Patocka wrote:
Note, that if a database uses buffered block device, performance will be
suboptimal, because the buffering mechanism can't create large bios, it
only sends page-sized bios. But that is expected to not be used - the
database should either use a block device with direct I/O or a filesystem
with or without direct I/O.
And, as pointed out in the private mail that John forwarded to the list
without my permission if we really have a workload that cares md could
Ah come on. I deleted most of the private thread....
implement the plugging callback as done in md to operate on a batch
of bios.
Also not building large bios is not a fundamental property of block
device writes but because it uses the legacy buffered head helpers.
That means:
a) the same is applicable to file systems using them as well
b) can be fixed if someone cares enough, but apparently no one does
OK. Thanks, that the info I was looking for.
Thanks,
/John
