diff options
| author | Peter Lieven <pl@kamp.de> | 2013-03-26 10:58:35 +0100 |
|---|---|---|
| committer | Juan Quintela <quintela@redhat.com> | 2013-03-26 13:32:32 +0100 |
| commit | 3edcd7e6ebae3ef0ac178eed5f4225803159562d (patch) | |
| tree | f8fd21342f83280a00e1515bf98e6633505a56e5 | |
| parent | 49f676a00ab540fac1d2008be26434cf85607722 (diff) | |
migration: search for zero instead of dup pages
virtually all dup pages are zero pages. remove
the special is_dup_page() function and use the
optimized buffer_find_nonzero_offset() function
instead.
here buffer_find_nonzero_offset() is used directly
to avoid the unnecssary additional checks in
buffer_is_zero().
raw performace gain checking 1 GByte zeroed memory
over is_dup_page() is approx. 10-12% with SSE2
and 8-10% with unsigned long arithmedtic.
Signed-off-by: Peter Lieven <pl@kamp.de>
Reviewed-by: Orit Wasserman <owasserm@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
| -rw-r--r-- | arch_init.c | 21 |
1 files changed, 6 insertions, 15 deletions
diff --git a/arch_init.c b/arch_init.c index 35974c2828..dd5deffa91 100644 --- a/arch_init.c +++ b/arch_init.c @@ -146,19 +146,10 @@ int qemu_read_default_config_files(bool userconfig) return 0; } -static int is_dup_page(uint8_t *page) +static inline bool is_zero_page(uint8_t *p) { - VECTYPE *p = (VECTYPE *)page; - VECTYPE val = SPLAT(page); - int i; - - for (i = 0; i < TARGET_PAGE_SIZE / sizeof(VECTYPE); i++) { - if (!ALL_EQ(val, p[i])) { - return 0; - } - } - - return 1; + return buffer_find_nonzero_offset(p, TARGET_PAGE_SIZE) == + TARGET_PAGE_SIZE; } /* struct contains XBZRLE cache and a static page @@ -445,12 +436,12 @@ static int ram_save_block(QEMUFile *f, bool last_stage) /* In doubt sent page as normal */ bytes_sent = -1; - if (is_dup_page(p)) { + if (is_zero_page(p)) { acct_info.dup_pages++; bytes_sent = save_block_hdr(f, block, offset, cont, RAM_SAVE_FLAG_COMPRESS); - qemu_put_byte(f, *p); - bytes_sent += 1; + qemu_put_byte(f, 0); + bytes_sent++; } else if (migrate_use_xbzrle()) { current_addr = block->offset + offset; bytes_sent = save_xbzrle_page(f, p, current_addr, block, |