diff options
| author | Wei Yang <richardw.yang@linux.intel.com> | 2019-08-06 08:46:47 +0800 |
|---|---|---|
| committer | Dr. David Alan Gilbert <dgilbert@redhat.com> | 2019-08-14 17:33:14 +0100 |
| commit | dad45ab2be9d5ce033ddba328204b06f2d10f0ed (patch) | |
| tree | 947efdd42eac7046c0475728365e9c82e75a0c19 /migration | |
| parent | 810cf2bbd4c5c1417bda8bec49caf0ababc22860 (diff) | |
migration/postcopy: simplify calculation of run_start and fixup_start_addr
The purpose of the calculation is to find a HostPage which is partially
dirty.
* fixup_start_addr points to the start of the HostPage to discard
* run_start points to the next HostPage to check
While in the middle stage, there would two cases for run_start:
* aligned with HostPage means this is not partially dirty
* not aligned means this is partially dirty
When it is aligned, no work and calculation is necessary. run_start
already points to the start of next HostPage and is ready to continue.
When it is not aligned, the calculation could be simplified with:
* fixup_start_addr = QEMU_ALIGN_DOWN(run_start, host_ratio)
* run_start = QEMU_ALIGN_UP(run_start, host_ratio)
By doing so, run_start always points to the next HostPage to check.
fixup_start_addr always points to the HostPage to discard.
Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Message-Id: <20190806004648.8659-2-richardw.yang@linux.intel.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Diffstat (limited to 'migration')
| -rw-r--r-- | migration/ram.c | 34 |
1 files changed, 7 insertions, 27 deletions
diff --git a/migration/ram.c b/migration/ram.c index f428639af5..d2184c3cfc 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -2955,7 +2955,6 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass, } while (run_start < pages) { - unsigned long fixup_start_addr; unsigned long host_offset; /* @@ -2963,45 +2962,26 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass, * page, then we need to fixup this host page. */ host_offset = run_start % host_ratio; - if (host_offset) { - fixup_start_addr = run_start - host_offset; - /* - * This host page has gone, the next loop iteration starts - * from after the fixup - */ - run_start = fixup_start_addr + host_ratio; - } else { + if (!host_offset) { /* Find the end of this run */ - unsigned long run_end; if (unsent_pass) { - run_end = find_next_bit(unsentmap, pages, run_start + 1); + run_start = find_next_bit(unsentmap, pages, run_start + 1); } else { - run_end = find_next_zero_bit(bitmap, pages, run_start + 1); + run_start = find_next_zero_bit(bitmap, pages, run_start + 1); } /* * If the end isn't at the start of a host page, then the * run doesn't finish at the end of a host page * and we need to discard. */ - host_offset = run_end % host_ratio; - if (host_offset) { - fixup_start_addr = run_end - host_offset; - /* - * This host page has gone, the next loop iteration starts - * from after the fixup - */ - run_start = fixup_start_addr + host_ratio; - } else { - /* - * No discards on this iteration, next loop starts from - * next sent/dirty page - */ - run_start = run_end + 1; - } + host_offset = run_start % host_ratio; } if (host_offset) { unsigned long page; + unsigned long fixup_start_addr = QEMU_ALIGN_DOWN(run_start, + host_ratio); + run_start = QEMU_ALIGN_UP(run_start, host_ratio); /* Tell the destination to discard this page */ if (unsent_pass || !test_bit(fixup_start_addr, unsentmap)) { |