Commit 68851b98 authored by Paolo Bonzini's avatar Paolo Bonzini Committed by Michael Tokarev
Browse files

exec: avoid unnecessary cacheline bounce on ram_list.mru_block 



Whenever the MRU cache hits for the list of RAM blocks, qemu_get_ram_block
does an unnecessary write that causes a processor cache line to bounce
from one core to another.  This causes a performance hit.

Reported-by: default avatarEmilio G. Cota <cota@braap.org>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarMichael Tokarev <mjt@tls.msk.ru>
parent 74de807f

exec.c

+1 −1
Original line number Diff line number Diff line
@@ -903,7 +903,7 @@ static RAMBlock *qemu_get_ram_block(ram_addr_t addr) 


    block = atomic_rcu_read(&ram_list.mru_block);

    if (block && addr - block->offset < block->max_length) {

        goto found;

        return block;

    }

    QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {

        if (addr - block->offset < block->max_length) {