diff options
| author | Mike Christie <michael.christie@oracle.com> | 2024-12-03 13:15:14 -0600 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2025-02-25 07:10:46 -0500 |
| commit | fd47976581333765964f4ce0ea01176fa1e646d5 (patch) | |
| tree | ebdaa531e50bbd712b560893113a4f01eb522cff | |
| parent | ddc5b5f68ec553a037a822f81150acbbdefa3ad1 (diff) | |
vhost-scsi: Allocate iov_iter used for unaligned copies when needed
It's extremely rare that we get unaligned requests that need to drop
down to the data copy code path. However, the iov_iter is almost 5% of
the mem used for the vhost_scsi_cmd. This patch has us allocate the
iov_iter only when needed since it's not a perf path that uses the
struct. This along with the patches that removed the duplicated fields on
the vhost_scsd_cmd allow us to reduce mem use by 1 MB in mid size setups
where we have 16 virtqueues and are doing 1024 cmds per queue.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20241203191705.19431-8-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
| -rw-r--r-- | drivers/vhost/scsi.c | 26 |
1 files changed, 17 insertions, 9 deletions
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c index fbcdc9866e80..82389e2ac0c9 100644 --- a/drivers/vhost/scsi.c +++ b/drivers/vhost/scsi.c @@ -112,8 +112,8 @@ struct vhost_scsi_cmd { u32 tvc_sgl_count; u32 tvc_prot_sgl_count; u32 copied_iov:1; - const void *saved_iter_addr; - struct iov_iter saved_iter; + const void *read_iov; + struct iov_iter *read_iter; struct scatterlist *sgl; struct sg_table table; struct scatterlist *prot_sgl; @@ -378,7 +378,8 @@ static void vhost_scsi_release_cmd_res(struct se_cmd *se_cmd) else put_page(page); } - kfree(tv_cmd->saved_iter_addr); + kfree(tv_cmd->read_iter); + kfree(tv_cmd->read_iov); sg_free_table_chained(&tv_cmd->table, vs->inline_sg_cnt); } if (tv_cmd->tvc_prot_sgl_count) { @@ -576,7 +577,7 @@ static void vhost_scsi_evt_work(struct vhost_work *work) static int vhost_scsi_copy_sgl_to_iov(struct vhost_scsi_cmd *cmd) { - struct iov_iter *iter = &cmd->saved_iter; + struct iov_iter *iter = cmd->read_iter; struct scatterlist *sg; struct page *page; size_t len; @@ -624,7 +625,7 @@ static void vhost_scsi_complete_cmd_work(struct vhost_work *work) cmd, se_cmd->residual_count, se_cmd->scsi_status); memset(&v_rsp, 0, sizeof(v_rsp)); - if (cmd->saved_iter_addr && vhost_scsi_copy_sgl_to_iov(cmd)) { + if (cmd->read_iter && vhost_scsi_copy_sgl_to_iov(cmd)) { v_rsp.response = VIRTIO_SCSI_S_BAD_TARGET; } else { v_rsp.resid = cpu_to_vhost32(cmd->tvc_vq, @@ -808,10 +809,15 @@ vhost_scsi_copy_iov_to_sgl(struct vhost_scsi_cmd *cmd, struct iov_iter *iter, int i, ret; if (data_dir == DMA_FROM_DEVICE) { - cmd->saved_iter_addr = dup_iter(&cmd->saved_iter, iter, - GFP_KERNEL); - if (!cmd->saved_iter_addr) + cmd->read_iter = kzalloc(sizeof(*cmd->read_iter), GFP_KERNEL); + if (!cmd->read_iter) return -ENOMEM; + + cmd->read_iov = dup_iter(cmd->read_iter, iter, GFP_KERNEL); + if (!cmd->read_iov) { + ret = -ENOMEM; + goto free_iter; + } } for_each_sgtable_sg(sg_table, sg, i) { @@ -845,7 +851,9 @@ err: if (page) __free_page(page); } - kfree(cmd->saved_iter_addr); + kfree(cmd->read_iov); +free_iter: + kfree(cmd->read_iter); return ret; } |