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Commit 5f544cfa authored by Nicholas Bellinger's avatar Nicholas Bellinger Committed by Nicholas Bellinger
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tcm_fc: Convert to per-cpu command map pre-allocation of ft_cmd 



This patch converts tcm_fc to use transport_init_session_tags()
pre-allocation logic for struct ft_cmd descriptors using per-cpu
session tag pooling in order to effectively avoid memory allocation
+ release for each received I/O.

It adds percpu_ida_alloc() in ft_recv_cmd() to obtain an tag and
locate ft_cmd from se_sess->sess_cmd_map[], and percpu_ida_free()
in ft_free_cmd() to release the tag based upon se_cmd->map_tag id.

It also uses a TCM_FC_DEFAULT_TAGS value of 512, that puts the
per se_sess->sess_cmd_map allocation at ~360K on 64-bit.

v2 changes:

  - Handle possible tag < 0 failure with GFP_ATOMIC

Cc: Mark Rustad <mark.d.rustad@intel.com>
Cc: Robert Love <robert.w.love@intel.com>
Cc: Kent Overstreet <kmo@daterainc.com>
Signed-off-by: default avatarNicholas Bellinger <nab@daterainc.com>
parent 15c03dd4

drivers/target/tcm_fc/tcm_fc.h

+1 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
#define FT_NAMELEN 32		/* length of ASCII WWPNs including pad */

#define FT_TPG_NAMELEN 32	/* max length of TPG name */

#define FT_LUN_NAMELEN 32	/* max length of LUN name */

#define TCM_FC_DEFAULT_TAGS 512	/* tags used for per-session preallocation */



struct ft_transport_id {

	__u8	format;

drivers/target/tcm_fc/tfc_cmd.c

+14 −4
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 
#include <linux/configfs.h>

#include <linux/ctype.h>

#include <linux/hash.h>

#include <linux/percpu_ida.h>

#include <asm/unaligned.h>

#include <scsi/scsi.h>

#include <scsi/scsi_host.h>
@@ -89,16 +90,18 @@ static void ft_free_cmd(struct ft_cmd *cmd) 
{

	struct fc_frame *fp;

	struct fc_lport *lport;

	struct se_session *se_sess;



	if (!cmd)

		return;

	se_sess = cmd->sess->se_sess;

	fp = cmd->req_frame;

	lport = fr_dev(fp);

	if (fr_seq(fp))

		lport->tt.seq_release(fr_seq(fp));

	fc_frame_free(fp);

	percpu_ida_free(&se_sess->sess_tag_pool, cmd->se_cmd.map_tag);

	ft_sess_put(cmd->sess);	/* undo get from lookup at recv */

	kfree(cmd);

}



void ft_release_cmd(struct se_cmd *se_cmd)
@@ -432,14 +435,21 @@ static void ft_recv_cmd(struct ft_sess *sess, struct fc_frame *fp) 
{

	struct ft_cmd *cmd;

	struct fc_lport *lport = sess->tport->lport;

	struct se_session *se_sess = sess->se_sess;

	int tag;



	cmd = kzalloc(sizeof(*cmd), GFP_ATOMIC);

	if (!cmd)

	tag = percpu_ida_alloc(&se_sess->sess_tag_pool, GFP_ATOMIC);

	if (tag < 0)

		goto busy;



	cmd = &((struct ft_cmd *)se_sess->sess_cmd_map)[tag];

	memset(cmd, 0, sizeof(struct ft_cmd));



	cmd->se_cmd.map_tag = tag;

	cmd->sess = sess;

	cmd->seq = lport->tt.seq_assign(lport, fp);

	if (!cmd->seq) {

		kfree(cmd);

		percpu_ida_free(&se_sess->sess_tag_pool, tag);

		goto busy;

	}

	cmd->req_frame = fp;		/* hold frame during cmd */

drivers/target/tcm_fc/tfc_sess.c

+2 −1
Original line number Diff line number Diff line
@@ -210,7 +210,8 @@ static struct ft_sess *ft_sess_create(struct ft_tport *tport, u32 port_id, 
	if (!sess)

		return NULL;



	sess->se_sess = transport_init_session();

	sess->se_sess = transport_init_session_tags(TCM_FC_DEFAULT_TAGS,

						    sizeof(struct ft_cmd));

	if (IS_ERR(sess->se_sess)) {

		kfree(sess);

		return NULL;