| Message ID | 20171010181542.24168-7-quintela@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | Make xbzrle_cache_size a migration parameter | expand |
On Tue, Oct 10, 2017 at 08:15:38PM +0200, Juan Quintela wrote: > Instead of passing silently round down the number of pages, make it an > error that the cache size is not a multiple of 2. s/multiple/power/? Would this patch break existing users? > > Signed-off-by: Juan Quintela <quintela@redhat.com> > --- > migration/page_cache.c | 12 +++++++----- > 1 file changed, 7 insertions(+), 5 deletions(-) > > diff --git a/migration/page_cache.c b/migration/page_cache.c > index 9a9d13d6a2..96268c3aea 100644 > --- a/migration/page_cache.c > +++ b/migration/page_cache.c > @@ -58,6 +58,13 @@ PageCache *cache_init(int64_t new_size, size_t page_size, Error **errp) > return NULL; > } > > + /* round down to the nearest power of 2 */ > + if (!is_power_of_2(num_pages)) { > + error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cache size", > + "is not a power of two number of pages"); > + return NULL; > + } > + > /* We prefer not to abort if there is no memory */ > cache = g_try_malloc(sizeof(*cache)); > if (!cache) { > @@ -65,11 +72,6 @@ PageCache *cache_init(int64_t new_size, size_t page_size, Error **errp) > "Failed to allocate cache"); > return NULL; > } > - /* round down to the nearest power of 2 */ > - if (!is_power_of_2(num_pages)) { > - num_pages = pow2floor(num_pages); > - DPRINTF("rounding down to %" PRId64 "\n", num_pages); > - } > cache->page_size = page_size; > cache->num_items = 0; > cache->max_num_items = num_pages; > -- > 2.13.6 >
Peter Xu <peterx@redhat.com> wrote: > On Tue, Oct 10, 2017 at 08:15:38PM +0200, Juan Quintela wrote: >> Instead of passing silently round down the number of pages, make it an >> error that the cache size is not a multiple of 2. > > s/multiple/power/? Thanks. > Would this patch break existing users? I have a problem here. Current code: - "silently" truncate the value that we pass - "silently" uses a different value that the one that it shows as used - "shows" a value that is different of what has been set to So, I have to break one of them: - only allow valid values (and then we output the same value that user input) - store "setup" value, and use something different "internaly" No clear winner. This way we are at least consistent with everything else. Documentation already required a power of 2 value. And we give a good error message. Later, Juan. > >> >> Signed-off-by: Juan Quintela <quintela@redhat.com> >> --- >> migration/page_cache.c | 12 +++++++----- >> 1 file changed, 7 insertions(+), 5 deletions(-) >> >> diff --git a/migration/page_cache.c b/migration/page_cache.c >> index 9a9d13d6a2..96268c3aea 100644 >> --- a/migration/page_cache.c >> +++ b/migration/page_cache.c >> @@ -58,6 +58,13 @@ PageCache *cache_init(int64_t new_size, size_t page_size, Error **errp) >> return NULL; >> } >> >> + /* round down to the nearest power of 2 */ >> + if (!is_power_of_2(num_pages)) { >> + error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cache size", >> + "is not a power of two number of pages"); >> + return NULL; >> + } >> + >> /* We prefer not to abort if there is no memory */ >> cache = g_try_malloc(sizeof(*cache)); >> if (!cache) { >> @@ -65,11 +72,6 @@ PageCache *cache_init(int64_t new_size, size_t page_size, Error **errp) >> "Failed to allocate cache"); >> return NULL; >> } >> - /* round down to the nearest power of 2 */ >> - if (!is_power_of_2(num_pages)) { >> - num_pages = pow2floor(num_pages); >> - DPRINTF("rounding down to %" PRId64 "\n", num_pages); >> - } >> cache->page_size = page_size; >> cache->num_items = 0; >> cache->max_num_items = num_pages; >> -- >> 2.13.6 >>
diff --git a/migration/page_cache.c b/migration/page_cache.c index 9a9d13d6a2..96268c3aea 100644 --- a/migration/page_cache.c +++ b/migration/page_cache.c @@ -58,6 +58,13 @@ PageCache *cache_init(int64_t new_size, size_t page_size, Error **errp) return NULL; } + /* round down to the nearest power of 2 */ + if (!is_power_of_2(num_pages)) { + error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "cache size", + "is not a power of two number of pages"); + return NULL; + } + /* We prefer not to abort if there is no memory */ cache = g_try_malloc(sizeof(*cache)); if (!cache) { @@ -65,11 +72,6 @@ PageCache *cache_init(int64_t new_size, size_t page_size, Error **errp) "Failed to allocate cache"); return NULL; } - /* round down to the nearest power of 2 */ - if (!is_power_of_2(num_pages)) { - num_pages = pow2floor(num_pages); - DPRINTF("rounding down to %" PRId64 "\n", num_pages); - } cache->page_size = page_size; cache->num_items = 0; cache->max_num_items = num_pages;
Instead of passing silently round down the number of pages, make it an error that the cache size is not a multiple of 2. Signed-off-by: Juan Quintela <quintela@redhat.com> --- migration/page_cache.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)