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Tue, 15 May 2018 12:11:22 -0400 Received: from mail-it0-f65.google.com ([209.85.214.65]:55478 "EHLO mail-it0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752972AbeEOQLT (ORCPT ); Tue, 15 May 2018 12:11:19 -0400 X-Google-Smtp-Source: AB8JxZr4z+xyR3CPEpa0V2oC4RWOj8NbBnJW/DWEDcUpyAF5oHVwgE0qMIigjX9WJ7DNco29lnj5Wg== Subject: Re: [PATCH 1/2] Convert target drivers to use sbitmap To: Matthew Wilcox , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, linux1394-devel@lists.sourceforge.net, linux-usb@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, Juergen Gross , qla2xxx-upstream@qlogic.com, Kent Overstreet Cc: Matthew Wilcox References: <20180515160043.27044-1-willy@infradead.org> <20180515160043.27044-2-willy@infradead.org> From: Jens Axboe Message-ID: <3a56027b-47bc-dcb8-a465-3670031572f1@kernel.dk> Date: Tue, 15 May 2018 10:11:15 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.0 MIME-Version: 1.0 In-Reply-To: <20180515160043.27044-2-willy@infradead.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-usb-owner@vger.kernel.org X-Mailing-List: linux-usb@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On 5/15/18 10:00 AM, Matthew Wilcox wrote: > From: Matthew Wilcox > > The sbitmap and the percpu_ida perform essentially the same task, > allocating tags for commands. Since the sbitmap is more used than > the percpu_ida, convert the percpu_ida users to the sbitmap API. It should also be the same performance as percpu_ida in light use, and performs much better at > 50% utilization of the tag space. I think that's better justification than "more used than". > diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c > index 4435bf374d2d..28bcffae609f 100644 > --- a/drivers/target/iscsi/iscsi_target_util.c > +++ b/drivers/target/iscsi/iscsi_target_util.c > @@ -17,7 +17,7 @@ > ******************************************************************************/ > > #include > -#include > +#include > #include /* ipv6_addr_equal() */ > #include > #include > @@ -147,6 +147,28 @@ void iscsit_free_r2ts_from_list(struct iscsi_cmd *cmd) > spin_unlock_bh(&cmd->r2t_lock); > } > > +int iscsit_wait_for_tag(struct se_session *se_sess, int state, int *cpup) > +{ > + int tag = -1; > + DEFINE_WAIT(wait); > + struct sbq_wait_state *ws; > + > + if (state == TASK_RUNNING) > + return tag; > + > + ws = &se_sess->sess_tag_pool.ws[0]; > + for (;;) { > + prepare_to_wait_exclusive(&ws->wait, &wait, state); > + if (signal_pending_state(state, current)) > + break; > + schedule(); > + tag = sbitmap_queue_get(&se_sess->sess_tag_pool, cpup); > + } > + > + finish_wait(&ws->wait, &wait); > + return tag; > +} Seems like that should be: ws = &se_sess->sess_tag_pool.ws[0]; for (;;) { prepare_to_wait_exclusive(&ws->wait, &wait, state); if (signal_pending_state(state, current)) break; tag = sbitmap_queue_get(&se_sess->sess_tag_pool, cpup); if (tag != -1) break; schedule(); } finish_wait(&ws->wait, &wait); return tag; > /* > * May be called from software interrupt (timer) context for allocating > * iSCSI NopINs. > @@ -155,9 +177,11 @@ struct iscsi_cmd *iscsit_allocate_cmd(struct iscsi_conn *conn, int state) > { > struct iscsi_cmd *cmd; > struct se_session *se_sess = conn->sess->se_sess; > - int size, tag; > + int size, tag, cpu; > > - tag = percpu_ida_alloc(&se_sess->sess_tag_pool, state); > + tag = sbitmap_queue_get(&se_sess->sess_tag_pool, &cpu); > + if (tag < 0) > + tag = iscsit_wait_for_tag(se_sess, state, &cpu); > if (tag < 0) > return NULL; Might make sense to just roll the whole thing into iscsi_get_tag(), that would be cleaner. sbitmap should provide a helper for that, but we can do that cleanup later. That would encapsulate things like the per-cpu caching hint too, for instance. Rest looks fine to me. -- Jens Axboe From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Date: Tue, 15 May 2018 16:11:15 +0000 Subject: Re: [PATCH 1/2] Convert target drivers to use sbitmap Message-Id: <3a56027b-47bc-dcb8-a465-3670031572f1@kernel.dk> List-Id: References: <20180515160043.27044-1-willy@infradead.org> <20180515160043.27044-2-willy@infradead.org> In-Reply-To: <20180515160043.27044-2-willy@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Matthew Wilcox , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, linux1394-devel@lists.sourceforge.net, linux-usb@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, Juergen Gross , qla2xxx-upstream@qlogic.com, Kent Overstreet Cc: Matthew Wilcox On 5/15/18 10:00 AM, Matthew Wilcox wrote: > From: Matthew Wilcox > > The sbitmap and the percpu_ida perform essentially the same task, > allocating tags for commands. Since the sbitmap is more used than > the percpu_ida, convert the percpu_ida users to the sbitmap API. It should also be the same performance as percpu_ida in light use, and performs much better at > 50% utilization of the tag space. I think that's better justification than "more used than". > diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c > index 4435bf374d2d..28bcffae609f 100644 > --- a/drivers/target/iscsi/iscsi_target_util.c > +++ b/drivers/target/iscsi/iscsi_target_util.c > @@ -17,7 +17,7 @@ > ******************************************************************************/ > > #include > -#include > +#include > #include /* ipv6_addr_equal() */ > #include > #include > @@ -147,6 +147,28 @@ void iscsit_free_r2ts_from_list(struct iscsi_cmd *cmd) > spin_unlock_bh(&cmd->r2t_lock); > } > > +int iscsit_wait_for_tag(struct se_session *se_sess, int state, int *cpup) > +{ > + int tag = -1; > + DEFINE_WAIT(wait); > + struct sbq_wait_state *ws; > + > + if (state = TASK_RUNNING) > + return tag; > + > + ws = &se_sess->sess_tag_pool.ws[0]; > + for (;;) { > + prepare_to_wait_exclusive(&ws->wait, &wait, state); > + if (signal_pending_state(state, current)) > + break; > + schedule(); > + tag = sbitmap_queue_get(&se_sess->sess_tag_pool, cpup); > + } > + > + finish_wait(&ws->wait, &wait); > + return tag; > +} Seems like that should be: ws = &se_sess->sess_tag_pool.ws[0]; for (;;) { prepare_to_wait_exclusive(&ws->wait, &wait, state); if (signal_pending_state(state, current)) break; tag = sbitmap_queue_get(&se_sess->sess_tag_pool, cpup); if (tag != -1) break; schedule(); } finish_wait(&ws->wait, &wait); return tag; > /* > * May be called from software interrupt (timer) context for allocating > * iSCSI NopINs. > @@ -155,9 +177,11 @@ struct iscsi_cmd *iscsit_allocate_cmd(struct iscsi_conn *conn, int state) > { > struct iscsi_cmd *cmd; > struct se_session *se_sess = conn->sess->se_sess; > - int size, tag; > + int size, tag, cpu; > > - tag = percpu_ida_alloc(&se_sess->sess_tag_pool, state); > + tag = sbitmap_queue_get(&se_sess->sess_tag_pool, &cpu); > + if (tag < 0) > + tag = iscsit_wait_for_tag(se_sess, state, &cpu); > if (tag < 0) > return NULL; Might make sense to just roll the whole thing into iscsi_get_tag(), that would be cleaner. sbitmap should provide a helper for that, but we can do that cleanup later. That would encapsulate things like the per-cpu caching hint too, for instance. Rest looks fine to me. -- Jens Axboe From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Subject: [1/2] Convert target drivers to use sbitmap From: Jens Axboe Message-Id: <3a56027b-47bc-dcb8-a465-3670031572f1@kernel.dk> Date: Tue, 15 May 2018 10:11:15 -0600 To: Matthew Wilcox , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, linux1394-devel@lists.sourceforge.net, linux-usb@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, Juergen Gross , qla2xxx-upstream@qlogic.com, Kent Overstreet Cc: Matthew Wilcox List-ID: T24gNS8xNS8xOCAxMDowMCBBTSwgTWF0dGhldyBXaWxjb3ggd3JvdGU6Cj4gRnJvbTogTWF0dGhl dyBXaWxjb3ggPG1hd2lsY294QG1pY3Jvc29mdC5jb20+Cj4gCj4gVGhlIHNiaXRtYXAgYW5kIHRo ZSBwZXJjcHVfaWRhIHBlcmZvcm0gZXNzZW50aWFsbHkgdGhlIHNhbWUgdGFzaywKPiBhbGxvY2F0 aW5nIHRhZ3MgZm9yIGNvbW1hbmRzLiAgU2luY2UgdGhlIHNiaXRtYXAgaXMgbW9yZSB1c2VkIHRo YW4KPiB0aGUgcGVyY3B1X2lkYSwgY29udmVydCB0aGUgcGVyY3B1X2lkYSB1c2VycyB0byB0aGUg c2JpdG1hcCBBUEkuCgpJdCBzaG91bGQgYWxzbyBiZSB0aGUgc2FtZSBwZXJmb3JtYW5jZSBhcyBw ZXJjcHVfaWRhIGluIGxpZ2h0IHVzZSwgYW5kCnBlcmZvcm1zIG11Y2ggYmV0dGVyIGF0ID4gNTAl IHV0aWxpemF0aW9uIG9mIHRoZSB0YWcgc3BhY2UuIEkgdGhpbmsKdGhhdCdzIGJldHRlciBqdXN0 aWZpY2F0aW9uIHRoYW4gIm1vcmUgdXNlZCB0aGFuIi4KCj4gZGlmZiAtLWdpdCBhL2RyaXZlcnMv dGFyZ2V0L2lzY3NpL2lzY3NpX3RhcmdldF91dGlsLmMgYi9kcml2ZXJzL3RhcmdldC9pc2NzaS9p c2NzaV90YXJnZXRfdXRpbC5jCj4gaW5kZXggNDQzNWJmMzc0ZDJkLi4yOGJjZmZhZTYwOWYgMTAw NjQ0Cj4gLS0tIGEvZHJpdmVycy90YXJnZXQvaXNjc2kvaXNjc2lfdGFyZ2V0X3V0aWwuYwo+ICsr KyBiL2RyaXZlcnMvdGFyZ2V0L2lzY3NpL2lzY3NpX3RhcmdldF91dGlsLmMKPiBAQCAtMTcsNyAr MTcsNyBAQAo+ICAgKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioq KioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqLwo+ICAKPiAgI2luY2x1ZGUgPGxpbnV4 L2xpc3QuaD4KPiAtI2luY2x1ZGUgPGxpbnV4L3BlcmNwdV9pZGEuaD4KPiArI2luY2x1ZGUgPGxp bnV4L3NjaGVkL3NpZ25hbC5oPgo+ICAjaW5jbHVkZSA8bmV0L2lwdjYuaD4gICAgICAgICAvKiBp cHY2X2FkZHJfZXF1YWwoKSAqLwo+ICAjaW5jbHVkZSA8c2NzaS9zY3NpX3RjcS5oPgo+ICAjaW5j bHVkZSA8c2NzaS9pc2NzaV9wcm90by5oPgo+IEBAIC0xNDcsNiArMTQ3LDI4IEBAIHZvaWQgaXNj c2l0X2ZyZWVfcjJ0c19mcm9tX2xpc3Qoc3RydWN0IGlzY3NpX2NtZCAqY21kKQo+ICAJc3Bpbl91 bmxvY2tfYmgoJmNtZC0+cjJ0X2xvY2spOwo+ICB9Cj4gIAo+ICtpbnQgaXNjc2l0X3dhaXRfZm9y X3RhZyhzdHJ1Y3Qgc2Vfc2Vzc2lvbiAqc2Vfc2VzcywgaW50IHN0YXRlLCBpbnQgKmNwdXApCj4g K3sKPiArCWludCB0YWcgPSAtMTsKPiArCURFRklORV9XQUlUKHdhaXQpOwo+ICsJc3RydWN0IHNi cV93YWl0X3N0YXRlICp3czsKPiArCj4gKwlpZiAoc3RhdGUgPT0gVEFTS19SVU5OSU5HKQo+ICsJ CXJldHVybiB0YWc7Cj4gKwo+ICsJd3MgPSAmc2Vfc2Vzcy0+c2Vzc190YWdfcG9vbC53c1swXTsK PiArCWZvciAoOzspIHsKPiArCQlwcmVwYXJlX3RvX3dhaXRfZXhjbHVzaXZlKCZ3cy0+d2FpdCwg JndhaXQsIHN0YXRlKTsKPiArCQlpZiAoc2lnbmFsX3BlbmRpbmdfc3RhdGUoc3RhdGUsIGN1cnJl bnQpKQo+ICsJCQlicmVhazsKPiArCQlzY2hlZHVsZSgpOwo+ICsJCXRhZyA9IHNiaXRtYXBfcXVl dWVfZ2V0KCZzZV9zZXNzLT5zZXNzX3RhZ19wb29sLCBjcHVwKTsKPiArCX0KPiArCj4gKwlmaW5p c2hfd2FpdCgmd3MtPndhaXQsICZ3YWl0KTsKPiArCXJldHVybiB0YWc7Cj4gK30KClNlZW1zIGxp a2UgdGhhdCBzaG91bGQgYmU6CgoKCXdzID0gJnNlX3Nlc3MtPnNlc3NfdGFnX3Bvb2wud3NbMF07 Cglmb3IgKDs7KSB7CgkJcHJlcGFyZV90b193YWl0X2V4Y2x1c2l2ZSgmd3MtPndhaXQsICZ3YWl0 LCBzdGF0ZSk7CgkJaWYgKHNpZ25hbF9wZW5kaW5nX3N0YXRlKHN0YXRlLCBjdXJyZW50KSkKCQkJ YnJlYWs7CgkJdGFnID0gc2JpdG1hcF9xdWV1ZV9nZXQoJnNlX3Nlc3MtPnNlc3NfdGFnX3Bvb2ws IGNwdXApOwoJCWlmICh0YWcgIT0gLTEpCgkJCWJyZWFrOwoJCXNjaGVkdWxlKCk7Cgl9CgoJZmlu aXNoX3dhaXQoJndzLT53YWl0LCAmd2FpdCk7CglyZXR1cm4gdGFnOwoKPiAgLyoKPiAgICogTWF5 IGJlIGNhbGxlZCBmcm9tIHNvZnR3YXJlIGludGVycnVwdCAodGltZXIpIGNvbnRleHQgZm9yIGFs bG9jYXRpbmcKPiAgICogaVNDU0kgTm9wSU5zLgo+IEBAIC0xNTUsOSArMTc3LDExIEBAIHN0cnVj dCBpc2NzaV9jbWQgKmlzY3NpdF9hbGxvY2F0ZV9jbWQoc3RydWN0IGlzY3NpX2Nvbm4gKmNvbm4s IGludCBzdGF0ZSkKPiAgewo+ICAJc3RydWN0IGlzY3NpX2NtZCAqY21kOwo+ICAJc3RydWN0IHNl X3Nlc3Npb24gKnNlX3Nlc3MgPSBjb25uLT5zZXNzLT5zZV9zZXNzOwo+IC0JaW50IHNpemUsIHRh ZzsKPiArCWludCBzaXplLCB0YWcsIGNwdTsKPiAgCj4gLQl0YWcgPSBwZXJjcHVfaWRhX2FsbG9j KCZzZV9zZXNzLT5zZXNzX3RhZ19wb29sLCBzdGF0ZSk7Cj4gKwl0YWcgPSBzYml0bWFwX3F1ZXVl X2dldCgmc2Vfc2Vzcy0+c2Vzc190YWdfcG9vbCwgJmNwdSk7Cj4gKwlpZiAodGFnIDwgMCkKPiAr CQl0YWcgPSBpc2NzaXRfd2FpdF9mb3JfdGFnKHNlX3Nlc3MsIHN0YXRlLCAmY3B1KTsKPiAgCWlm ICh0YWcgPCAwKQo+ICAJCXJldHVybiBOVUxMOwoKTWlnaHQgbWFrZSBzZW5zZSB0byBqdXN0IHJv bGwgdGhlIHdob2xlIHRoaW5nIGludG8gaXNjc2lfZ2V0X3RhZygpLCB0aGF0CndvdWxkIGJlIGNs ZWFuZXIuCgpzYml0bWFwIHNob3VsZCBwcm92aWRlIGEgaGVscGVyIGZvciB0aGF0LCBidXQgd2Ug Y2FuIGRvIHRoYXQgY2xlYW51cApsYXRlci4gVGhhdCB3b3VsZCBlbmNhcHN1bGF0ZSB0aGluZ3Mg bGlrZSB0aGUgcGVyLWNwdSBjYWNoaW5nIGhpbnQgdG9vLApmb3IgaW5zdGFuY2UuCgpSZXN0IGxv b2tzIGZpbmUgdG8gbWUuCg==