| Message ID | 20220920225106.48451-5-peterx@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | migration: Postcopy Preempt-Full | expand |
* Peter Xu (peterx@redhat.com) wrote: > Removing referencing to RAMState.f in compress_page_with_multi_thread() and > flush_compressed_data(). > > Compression code by default isn't compatible with having >1 channels (or it > won't currently know which channel to flush the compressed data), so to > make it simple we always flush on the default to_dst_file port until > someone wants to add >1 ports support, as rs->f right now can really > change (after postcopy preempt is introduced). > > There should be no functional change at all after patch applied, since as > long as rs->f referenced in compression code, it must be to_dst_file. > > Signed-off-by: Peter Xu <peterx@redhat.com> Yes, I think that's true - although I think we need to add checks to stop someone trying to enable compression+multifd? Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > --- > migration/ram.c | 12 +++++++----- > 1 file changed, 7 insertions(+), 5 deletions(-) > > diff --git a/migration/ram.c b/migration/ram.c > index 62ff2c1469..8303252b6d 100644 > --- a/migration/ram.c > +++ b/migration/ram.c > @@ -1461,6 +1461,7 @@ static bool save_page_use_compression(RAMState *rs); > > static void flush_compressed_data(RAMState *rs) > { > + MigrationState *ms = migrate_get_current(); > int idx, len, thread_count; > > if (!save_page_use_compression(rs)) { > @@ -1479,7 +1480,7 @@ static void flush_compressed_data(RAMState *rs) > for (idx = 0; idx < thread_count; idx++) { > qemu_mutex_lock(&comp_param[idx].mutex); > if (!comp_param[idx].quit) { > - len = qemu_put_qemu_file(rs->f, comp_param[idx].file); > + len = qemu_put_qemu_file(ms->to_dst_file, comp_param[idx].file); > /* > * it's safe to fetch zero_page without holding comp_done_lock > * as there is no further request submitted to the thread, > @@ -1498,11 +1499,11 @@ static inline void set_compress_params(CompressParam *param, RAMBlock *block, > param->offset = offset; > } > > -static int compress_page_with_multi_thread(RAMState *rs, RAMBlock *block, > - ram_addr_t offset) > +static int compress_page_with_multi_thread(RAMBlock *block, ram_addr_t offset) > { > int idx, thread_count, bytes_xmit = -1, pages = -1; > bool wait = migrate_compress_wait_thread(); > + MigrationState *ms = migrate_get_current(); > > thread_count = migrate_compress_threads(); > qemu_mutex_lock(&comp_done_lock); > @@ -1510,7 +1511,8 @@ retry: > for (idx = 0; idx < thread_count; idx++) { > if (comp_param[idx].done) { > comp_param[idx].done = false; > - bytes_xmit = qemu_put_qemu_file(rs->f, comp_param[idx].file); > + bytes_xmit = qemu_put_qemu_file(ms->to_dst_file, > + comp_param[idx].file); > qemu_mutex_lock(&comp_param[idx].mutex); > set_compress_params(&comp_param[idx], block, offset); > qemu_cond_signal(&comp_param[idx].cond); > @@ -2263,7 +2265,7 @@ static bool save_compress_page(RAMState *rs, RAMBlock *block, ram_addr_t offset) > return false; > } > > - if (compress_page_with_multi_thread(rs, block, offset) > 0) { > + if (compress_page_with_multi_thread(block, offset) > 0) { > return true; > } > > -- > 2.32.0 >
On Tue, Oct 04, 2022 at 11:54:02AM +0100, Dr. David Alan Gilbert wrote: > * Peter Xu (peterx@redhat.com) wrote: > > Removing referencing to RAMState.f in compress_page_with_multi_thread() and > > flush_compressed_data(). > > > > Compression code by default isn't compatible with having >1 channels (or it > > won't currently know which channel to flush the compressed data), so to > > make it simple we always flush on the default to_dst_file port until > > someone wants to add >1 ports support, as rs->f right now can really > > change (after postcopy preempt is introduced). > > > > There should be no functional change at all after patch applied, since as > > long as rs->f referenced in compression code, it must be to_dst_file. > > > > Signed-off-by: Peter Xu <peterx@redhat.com> > > Yes, I think that's true - although I think we need to add checks to > stop someone trying to enable compression+multifd? We could. I think they can be enabled and migration will just ignore the multifd feature as ram_save_target_page() handles compress earlier. Even if save_compress_page() fails with -EBUSY we'll still skip multifd: if (!save_page_use_compression(rs) && migrate_use_multifd() && !migration_in_postcopy()) { return ram_save_multifd_page(rs, block, offset); } Explicitly disable compression would be still cleaner, then we can even drop above check on save_page_use_compression(). Slight risk of breaking someone's config, but I don't think it should be majority. If that looks good, I can add one patch for it (probably in the other patchset, though, which I'll repost today). > > Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Thanks!
diff --git a/migration/ram.c b/migration/ram.c index 62ff2c1469..8303252b6d 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -1461,6 +1461,7 @@ static bool save_page_use_compression(RAMState *rs); static void flush_compressed_data(RAMState *rs) { + MigrationState *ms = migrate_get_current(); int idx, len, thread_count; if (!save_page_use_compression(rs)) { @@ -1479,7 +1480,7 @@ static void flush_compressed_data(RAMState *rs) for (idx = 0; idx < thread_count; idx++) { qemu_mutex_lock(&comp_param[idx].mutex); if (!comp_param[idx].quit) { - len = qemu_put_qemu_file(rs->f, comp_param[idx].file); + len = qemu_put_qemu_file(ms->to_dst_file, comp_param[idx].file); /* * it's safe to fetch zero_page without holding comp_done_lock * as there is no further request submitted to the thread, @@ -1498,11 +1499,11 @@ static inline void set_compress_params(CompressParam *param, RAMBlock *block, param->offset = offset; } -static int compress_page_with_multi_thread(RAMState *rs, RAMBlock *block, - ram_addr_t offset) +static int compress_page_with_multi_thread(RAMBlock *block, ram_addr_t offset) { int idx, thread_count, bytes_xmit = -1, pages = -1; bool wait = migrate_compress_wait_thread(); + MigrationState *ms = migrate_get_current(); thread_count = migrate_compress_threads(); qemu_mutex_lock(&comp_done_lock); @@ -1510,7 +1511,8 @@ retry: for (idx = 0; idx < thread_count; idx++) { if (comp_param[idx].done) { comp_param[idx].done = false; - bytes_xmit = qemu_put_qemu_file(rs->f, comp_param[idx].file); + bytes_xmit = qemu_put_qemu_file(ms->to_dst_file, + comp_param[idx].file); qemu_mutex_lock(&comp_param[idx].mutex); set_compress_params(&comp_param[idx], block, offset); qemu_cond_signal(&comp_param[idx].cond); @@ -2263,7 +2265,7 @@ static bool save_compress_page(RAMState *rs, RAMBlock *block, ram_addr_t offset) return false; } - if (compress_page_with_multi_thread(rs, block, offset) > 0) { + if (compress_page_with_multi_thread(block, offset) > 0) { return true; }
Removing referencing to RAMState.f in compress_page_with_multi_thread() and flush_compressed_data(). Compression code by default isn't compatible with having >1 channels (or it won't currently know which channel to flush the compressed data), so to make it simple we always flush on the default to_dst_file port until someone wants to add >1 ports support, as rs->f right now can really change (after postcopy preempt is introduced). There should be no functional change at all after patch applied, since as long as rs->f referenced in compression code, it must be to_dst_file. Signed-off-by: Peter Xu <peterx@redhat.com> --- migration/ram.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)