From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53780) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eZHJq-0003j5-GQ for qemu-devel@nongnu.org; Wed, 10 Jan 2018 09:25:31 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eZHJn-0000Zp-2k for qemu-devel@nongnu.org; Wed, 10 Jan 2018 09:25:30 -0500 Received: from mx1.redhat.com ([209.132.183.28]:54149) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eZHJm-0000Z7-LE for qemu-devel@nongnu.org; Wed, 10 Jan 2018 09:25:26 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id BBEA14E907 for ; Wed, 10 Jan 2018 14:25:25 +0000 (UTC) From: Paolo Bonzini Date: Wed, 10 Jan 2018 15:25:14 +0100 Message-Id: <20180110142515.13242-2-pbonzini@redhat.com> In-Reply-To: <20180110142515.13242-1-pbonzini@redhat.com> References: <20180110142515.13242-1-pbonzini@redhat.com> Subject: [Qemu-devel] [PATCH 1/2] find_ram_offset: Add comments and tracing List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: dgilbert@redhat.com, quintela@redhat.com, eblake@redhat.com From: "Dr. David Alan Gilbert" Add some comments and rename the "end" variable so I can understand the various nested loops. Add some tracing so I can see what they're doing. Signed-off-by: Dr. David Alan Gilbert Message-Id: <20180105170138.23357-2-dgilbert@redhat.com> Signed-off-by: Paolo Bonzini --- exec.c | 29 ++++++++++++++++++++++------- trace-events | 4 ++++ 2 files changed, 26 insertions(+), 7 deletions(-) diff --git a/exec.c b/exec.c index ff31e7165f..829f9d8d1a 100644 --- a/exec.c +++ b/exec.c @@ -1661,7 +1661,10 @@ static void *file_ram_alloc(RAMBlock *block, } #endif -/* Called with the ramlist lock held. */ +/* Allocate space within the ram_addr_t space that governs the + * dirty bitmaps. + * Called with the ramlist lock held. + */ static ram_addr_t find_ram_offset(ram_addr_t size) { RAMBlock *block, *next_block; @@ -1674,19 +1677,29 @@ static ram_addr_t find_ram_offset(ram_addr_t size) } RAMBLOCK_FOREACH(block) { - ram_addr_t end, next = RAM_ADDR_MAX; + ram_addr_t candidate, next = RAM_ADDR_MAX; - end = block->offset + block->max_length; + candidate = block->offset + block->max_length; + /* Search for the closest following block + * and find the gap. + */ RAMBLOCK_FOREACH(next_block) { - if (next_block->offset >= end) { + if (next_block->offset >= candidate) { next = MIN(next, next_block->offset); } } - if (next - end >= size && next - end < mingap) { - offset = end; - mingap = next - end; + + /* If it fits remember our place and remember the size + * of gap, but keep going so that we might find a smaller + * gap to fill so avoiding fragmentation. + */ + if (next - candidate >= size && next - candidate < mingap) { + offset = candidate; + mingap = next - candidate; } + + trace_find_ram_offset_loop(size, candidate, offset, next, mingap); } if (offset == RAM_ADDR_MAX) { @@ -1695,6 +1708,8 @@ static ram_addr_t find_ram_offset(ram_addr_t size) abort(); } + trace_find_ram_offset(size, offset); + return offset; } diff --git a/trace-events b/trace-events index 3695959d0a..a676b02a20 100644 --- a/trace-events +++ b/trace-events @@ -55,6 +55,10 @@ dma_complete(void *dbs, int ret, void *cb) "dbs=%p ret=%d cb=%p" dma_blk_cb(void *dbs, int ret) "dbs=%p ret=%d" dma_map_wait(void *dbs) "dbs=%p" +# # exec.c +find_ram_offset(uint64_t size, uint64_t offset) "size: 0x%"PRIx64 " @ 0x%"PRIx64 +find_ram_offset_loop(uint64_t size, uint64_t candidate, uint64_t offset, uint64_t next, uint64_t mingap) "trying size: 0x%"PRIx64 " @ 0x%"PRIx64 ," offset: 0x%"PRIx64" next: 0x%"PRIx64 " mingap: 0x%"PRIx64 + # memory.c memory_region_ops_read(int cpu_index, void *mr, uint64_t addr, uint64_t value, unsigned size) "cpu %d mr %p addr 0x%"PRIx64" value 0x%"PRIx64" size %u" memory_region_ops_write(int cpu_index, void *mr, uint64_t addr, uint64_t value, unsigned size) "cpu %d mr %p addr 0x%"PRIx64" value 0x%"PRIx64" size %u" -- 2.14.3