From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756831AbbFPQeO (ORCPT ); Tue, 16 Jun 2015 12:34:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47545 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756580AbbFPQds (ORCPT ); Tue, 16 Jun 2015 12:33:48 -0400 From: Igor Mammedov To: linux-kernel@vger.kernel.org Cc: mst@redhat.com, kvm@vger.kernel.org, pbonzini@redhat.com Subject: [PATCH 4/5] vhost: add per VQ memory region caching Date: Tue, 16 Jun 2015 18:33:38 +0200 Message-Id: <1434472419-148742-5-git-send-email-imammedo@redhat.com> In-Reply-To: <1434472419-148742-1-git-send-email-imammedo@redhat.com> References: <1434472419-148742-1-git-send-email-imammedo@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org that brings down translate_desc() cost to around 210ns if accessed descriptors are from the same memory region. Signed-off-by: Igor Mammedov --- that's what netperf/iperf workloads were during testing. --- drivers/vhost/vhost.c | 16 +++++++++++++--- drivers/vhost/vhost.h | 1 + 2 files changed, 14 insertions(+), 3 deletions(-) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 6a18c92..68c1c88 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -200,6 +200,7 @@ static void vhost_vq_reset(struct vhost_dev *dev, vq->call = NULL; vq->log_ctx = NULL; vq->memory = NULL; + vq->cached_reg = 0; } static int vhost_worker(void *data) @@ -649,6 +650,7 @@ static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m) for (i = 0; i < d->nvqs; ++i) { mutex_lock(&d->vqs[i]->mutex); d->vqs[i]->memory = newmem; + d->vqs[i]->cached_reg = 0; mutex_unlock(&d->vqs[i]->mutex); } kvfree(oldmem); @@ -936,11 +938,17 @@ done: EXPORT_SYMBOL_GPL(vhost_dev_ioctl); static const struct vhost_memory_region *find_region(struct vhost_memory *mem, - __u64 addr, __u32 len) + __u64 addr, __u32 len, + int *cached_reg) { const struct vhost_memory_region *reg; int start = 0, end = mem->nregions; + reg = mem->regions + *cached_reg; + if (likely(addr >= reg->guest_phys_addr && + reg->guest_phys_addr + reg->memory_size > addr)) + return reg; + while (start < end) { int slot = start + (end - start) / 2; reg = mem->regions + slot; @@ -952,8 +960,10 @@ static const struct vhost_memory_region *find_region(struct vhost_memory *mem, reg = mem->regions + start; if (addr >= reg->guest_phys_addr && - reg->guest_phys_addr + reg->memory_size > addr) + reg->guest_phys_addr + reg->memory_size > addr) { + *cached_reg = start; return reg; + } return NULL; } @@ -1107,7 +1117,7 @@ static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len, ret = -ENOBUFS; break; } - reg = find_region(mem, addr, len); + reg = find_region(mem, addr, len, &vq->cached_reg); if (unlikely(!reg)) { ret = -EFAULT; break; diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index 8c1c792..68bd00f 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -106,6 +106,7 @@ struct vhost_virtqueue { /* Log write descriptors */ void __user *log_base; struct vhost_log *log; + int cached_reg; }; struct vhost_dev { -- 1.8.3.1