return value when it could return 1 (indicating we should stop).
Fix a few instances of pager_open() / pager_close() not being called.
Actually use these routines for the environment variable printing code
I just committed.
The block cache implementation in loader has proven to be almost useless, and in worst case even slowing down the disk reads due to insufficient cache size and extra memory copy.
Also the current cache implementation does not cache reads from CDs, or work with zfs built on top of multiple disks.
Instead of an LRU, this code uses a simple hash (O(1) read from cache), and instead of a single global cache, a separate cache per block device.
The cache also implements limited read-ahead to increase performance.
To simplify read ahead management, the read ahead will not wrap over bcache end, so in worst case, single block physical read will be performed to fill the last block in bcache.
Booting from a virtual CD over IPMI:
0ms latency, before: 27 second, after: 7 seconds
60ms latency, before: over 12 minutes, after: under 5 minutes.
Submitted by: Toomas Soome <tsoome@me.com>
Reviewed by: delphij (previous version), emaste (previous version)
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D4713
The initial IOCTL implementation supports reading disk physical
geometry.
Two additional functions were added. They allow reading/writing raw
data to the disk (default partition).
Submitted by: Wojciech Macek <wma@semihalf.com>
Obtained from: Semihalf
Sponsored by: Juniper Networks Inc.
Differential Revision: https://reviews.freebsd.org/D4143
disk_open(). Very often this is called several times for one file.
This leads to reading partition table metadata for each call. To
reduce the number of disk I/O we have a simple block cache, but it
is very dumb and more than half of I/O operations related to reading
metadata, misses this cache.
Introduce new cache layer to resolve this problem. It is independent
and doesn't need initialization like bcache, and will work by default
for all loaders which use the new DISK API. A successful disk_open()
call to each new disk or partition produces new entry in the cache.
Even more, when disk was already open, now opening of any nested
partitions does not require reading top level partition table.
So, if without this cache, partition table metadata was read around
20-50 times during boot, now it reads only once. This affects the booting
from GPT and MBR from the UFS.
number is not exactly specified. When the disk has MBR, also try to read
BSD label after ptable_getpart() call. When the disk has GPT, also set
d_partition to 255. Mostly, this is how it worked before.
When we open the disk, check the type of partition table, that has
been detected. If this is BSD label, then we assume this is DD mode.
Reported by: dim@
It uses new API from the part.c to work with partition tables.
Update userboot's disk driver to use new API. Note that struct
loader_callbacks_v1 has changed.
