perf blames the SEARCH_V2 ioctl wrapper for a lot of time spent in malloc.
Use a thread_local buffer for ioctl results, and reuse it between runs.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
(cherry picked from commit e509210428)
This gets rid of some more big memsets. It may replace them
with a lot of tiny mallocs, though. If this turns out to be
a bad idea then at least we can easily revert the change.
We really do need some large buffers for BtrfsIoctlSearchKey in some
cases, but we don't need to zero them out first. Don't do that so we
save some CPU.
Reduce the default buffer size to 4K because most BISK users don't get
need much more than 1K. Set the buffer size explicitly to the product of
the number of items and the desired item size in the places that really
need a lot of items.
I accidentally did a pre-push verification on a 32-bit build host.
There were a surprisingly small number of problems, so fix them.
Bees now builds on a 32-bit host. Let's not update README just yet,
though: the 32-bit ioctl support fails immediately after startup on a
64-bit kernel.
