There are no users left of version_find_latest(), version_test_gt(), and
version_test_numeric(). Remove those unused helper functions. Using
those helper functions is what caused the quadratic sorting performance
issues in the first place, so removing them is a net win.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Robbie Harwood <rharwood@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
The current implementation of the 10_kfreebsd script implements its menu
items sorting in bash with a quadratic algorithm, calling "sed", "sort",
"head", and "grep" to compare versions between individual lines, which
is annoyingly slow for kernel developers who can easily end up with
50-100 kernels in their boot partition.
This fix is ported from the 10_linux script, which has a similar
quadratic code pattern.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: debian-bsd@lists.debian.org
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
The current implementation of the 10_hurd script implements its menu
items sorting in bash with a quadratic algorithm, calling "sed", "sort",
"head", and "grep" to compare versions between individual lines, which
is annoyingly slow for kernel developers who can easily end up with
50-100 kernels in their boot partition.
This fix is ported from the 10_linux script, which has a similar
quadratic code pattern.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Samuel Thibault <samuel.thibault@ens-lyon.org>
Tested-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
The current implementation of the 20_linux_xen script implements its
menu items sorting in bash with a quadratic algorithm, calling "sed",
"sort", "head", and "grep" to compare versions between individual lines,
which is annoyingly slow for kernel developers who can easily end up
with 50-100 kernels in their boot partition.
This fix is ported from the 10_linux script, which has a similar
quadratic code pattern.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: xen-devel@lists.xenproject.org
Tested-by: Jason Andryuk <jandryuk@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
The current implementation of the 10_linux script implements its menu
items sorting in bash with a quadratic algorithm, calling "sed", "sort",
"head", and "grep" to compare versions between individual lines, which
is annoyingly slow for kernel developers who can easily end up with
50-100 kernels in /boot.
As an example, on a Intel(R) Core(TM) i7-8650U CPU @ 1.90GHz, running:
/usr/sbin/grub-mkconfig > /dev/null
With 44 kernels in /boot, this command takes 10-15 seconds to complete.
After this fix, the same command runs in 5 seconds.
With 116 kernels in /boot, this command takes 40 seconds to complete.
After this fix, the same command runs in 8 seconds.
For reference, the quadratic algorithm here is:
while [ "x$list" != "x" ] ; do <--- outer loop
linux=`version_find_latest $list`
version_find_latest()
for i in "$@" ; do <--- inner loop
version_test_gt()
fork+exec sed
version_test_numeric()
version_sort
fork+exec sort
fork+exec head -n 1
fork+exec grep
list=`echo $list | tr ' ' '\n' | fgrep -vx "$linux" | tr '\n' ' '`
tr
fgrep
tr
So all commands executed under version_test_gt() are executed
O(n^2) times where n is the number of kernel images in /boot.
Here is the improved algorithm proposed:
- Prepare a list with all the relevant information for ordering by a single
sort(1) execution. This is done by renaming ".old" suffixes by " 1" and
by suffixing all other files with " 2", thus making sure the ".old" entries
will follow the non-old entries in reverse-sorted-order.
- Call version_reverse_sort on the list (sort -r -V): A single execution of
sort(1). For instance, GNU coreutils' sort will reverse-sort the list in
O(n*log(n)) with a merge sort.
- Replace the " 1" suffixes by ".old", and remove the " 2" suffixes.
- Iterate on the reverse-sorted list to output each menu entry item.
Therefore, the algorithm proposed has O(n*log(n)) complexity with GNU
coreutils' sort compared to the prior O(n^2) complexity. Moreover, the
constant time required for each list entry is much less because sorting
is done within a single execution of sort(1) rather than requiring
O(n^2) executions of sed(1), sort(1), head(1), and grep(1) in
sub-shells.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Robbie Harwood <rharwood@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Mathieu Desnoyers