From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34584) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XYwUx-0006sO-10 for qemu-devel@nongnu.org; Tue, 30 Sep 2014 08:25:52 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XYwUn-0002yH-6x for qemu-devel@nongnu.org; Tue, 30 Sep 2014 08:25:42 -0400 Received: from mail-wg0-x22f.google.com ([2a00:1450:400c:c00::22f]:32843) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XYwUm-0002xk-Vo for qemu-devel@nongnu.org; Tue, 30 Sep 2014 08:25:33 -0400 Received: by mail-wg0-f47.google.com with SMTP id x13so250209wgg.6 for ; Tue, 30 Sep 2014 05:25:27 -0700 (PDT) Sender: Paolo Bonzini From: Paolo Bonzini Date: Tue, 30 Sep 2014 14:24:41 +0200 Message-Id: <1412079919-18857-2-git-send-email-pbonzini@redhat.com> In-Reply-To: <1412079919-18857-1-git-send-email-pbonzini@redhat.com> References: <1412079919-18857-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PULL 01/39] scsi: Optimize scsi_req_alloc List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Fam Zheng From: Fam Zheng Zeroing sense buffer for each scsi request is not efficient, we can just leave it uninitialized because sense_len is set to 0. Move the implicitly zeroed fields to the end of the structure and use a partial memset. The explicitly initialized fields (by scsi_req_alloc or scsi_req_new) are moved to the beginning of the structure, before sense buffer, to skip the memset. Also change g_malloc0 to g_slice_alloc. Signed-off-by: Fam Zheng Signed-off-by: Paolo Bonzini --- hw/scsi/scsi-bus.c | 8 +++++--- include/hw/scsi/scsi.h | 21 ++++++++++++++------- 2 files changed, 19 insertions(+), 10 deletions(-) diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c index 954c607..af293b5 100644 --- a/hw/scsi/scsi-bus.c +++ b/hw/scsi/scsi-bus.c @@ -551,8 +551,11 @@ SCSIRequest *scsi_req_alloc(const SCSIReqOps *reqops, SCSIDevice *d, SCSIRequest *req; SCSIBus *bus = scsi_bus_from_device(d); BusState *qbus = BUS(bus); + const int memset_off = offsetof(SCSIRequest, sense) + + sizeof(req->sense); - req = g_malloc0(reqops->size); + req = g_slice_alloc(reqops->size); + memset((uint8_t *)req + memset_off, 0, reqops->size - memset_off); req->refcount = 1; req->bus = bus; req->dev = d; @@ -560,7 +563,6 @@ SCSIRequest *scsi_req_alloc(const SCSIReqOps *reqops, SCSIDevice *d, req->lun = lun; req->hba_private = hba_private; req->status = -1; - req->sense_len = 0; req->ops = reqops; object_ref(OBJECT(d)); object_ref(OBJECT(qbus->parent)); @@ -1603,7 +1605,7 @@ void scsi_req_unref(SCSIRequest *req) } object_unref(OBJECT(req->dev)); object_unref(OBJECT(qbus->parent)); - g_free(req); + g_slice_free1(req->ops->size, req); } } diff --git a/include/hw/scsi/scsi.h b/include/hw/scsi/scsi.h index 2e3a8f9..6271ad3 100644 --- a/include/hw/scsi/scsi.h +++ b/include/hw/scsi/scsi.h @@ -50,17 +50,24 @@ struct SCSIRequest { uint32_t tag; uint32_t lun; uint32_t status; + void *hba_private; size_t resid; SCSICommand cmd; + + /* Note: + * - fields before sense are initialized by scsi_req_alloc; + * - sense[] is uninitialized; + * - fields after sense are memset to 0 by scsi_req_alloc. + * */ + + uint8_t sense[SCSI_SENSE_BUF_SIZE]; + uint32_t sense_len; + bool enqueued; + bool io_canceled; + bool retry; + bool dma_started; BlockDriverAIOCB *aiocb; QEMUSGList *sg; - bool dma_started; - uint8_t sense[SCSI_SENSE_BUF_SIZE]; - uint32_t sense_len; - bool enqueued; - bool io_canceled; - bool retry; - void *hba_private; QTAILQ_ENTRY(SCSIRequest) next; }; -- 1.8.3.1