diff for duplicates of <1504575610.3360.7.camel@wdc.com> diff --git a/a/1.txt b/N1/1.txt index cb74d77..a0b5c6f 100644 --- a/a/1.txt +++ b/N1/1.txt @@ -1,20 +1,20 @@ -T24gVHVlLCAyMDE3LTA5LTA1IGF0IDAwOjA4ICswODAwLCBNaW5nIExlaSB3cm90ZToNCj4gT24g -TW9uLCBTZXAgMDQsIDIwMTcgYXQgMDM6NDA6MzVQTSArMDAwMCwgQmFydCBWYW4gQXNzY2hlIHdy -b3RlOg0KPiA+IEhhdmUgeW91IGNvbnNpZGVyZWQgdG8gdXNlIHRoZSBibGstbXEgInJlc2VydmVk -IHJlcXVlc3QiIG1lY2hhbmlzbSB0byBhdm9pZA0KPiA+IHN0YXJ2YXRpb24gb2YgcG93ZXIgbWFu -YWdlbWVudCByZXF1ZXN0cyBpbnN0ZWFkIG9mIG1ha2luZyB0aGUgYmxvY2sgbGF5ZXINCj4gPiBl -dmVuIG1vcmUgY29tcGxpY2F0ZWQgdGhhbiBpdCBhbHJlYWR5IGlzPw0KPiANCj4gcmVzZXJ2ZWQg -cmVxdWVzdCBpcyByZWFsbHkgYSBiYWQgaWRlYSwgdGhhdCBtZWFucyB0aGUgcmVzZXJ2ZWQgcmVx -dWVzdA0KPiBjYW4ndCBiZSB1c2VkIGZvciBub3JtYWwgSS9PLCB3ZSBhbGwga25vdyB0aGUgcmVx -dWVzdC90YWcgc3BhY2UgaXMNCj4gcHJlY2lvdXMsIGFuZCBzb21lIGRldmljZSBoYXMgYSBxdWl0 -ZSBzbWFsbCB0YWcgc3BhY2UsIHN1Y2ggYXMgc2F0YS4NCj4gVGhpcyB3YXkgd2lsbCBhZmZlY3Qg -cGVyZm9ybWFuY2UgZGVmaW5pdGVseS4NCg0KU29ycnkgYnV0IEknbSBuZWl0aGVyIGNvbnZpbmNl -ZCB0aGF0IHJlc2VydmluZyBhIHJlcXVlc3QgZm9yIHBvd2VyIG1hbmFnZW1lbnQgDQp3b3VsZCBi -ZSBhIGJhZCBpZGVhIG5vciB0aGF0IGl0IHdvdWxkIGhhdmUgYSBzaWduaWZpY2FudCBwZXJmb3Jt -YW5jZSBpbXBhY3Qgbm9yDQp0aGF0IGl0IHdvdWxkIGJlIGNvbXBsaWNhdGVkIHRvIGltcGxlbWVu -dC4gSGF2ZSB5b3Ugbm90aWNlZCB0aGF0IHRoZSBMaW51eCBBVEENCmltcGxlbWVudGF0aW9uIGFs -cmVhZHkgcmVzZXJ2ZXMgYSByZXF1ZXN0IGZvciBpbnRlcm5hbCB1c2UgYW5kIHRoZXJlYnkgcmVk -dWNlcw0KdGhlIHF1ZXVlIGRlcHRoIGZyb20gMzIgdG8gMzEgKHNlZSBhbHNvIEFUQV9UQUdfSU5U -RVJOQUwpPyBXaGF0IEkgd291bGQgbGlrZSB0bw0Ka25vdyBpZiBpcyB3aGV0aGVyIHRoZSBwZXJm -b3JtYW5jZSBpbXBhY3Qgb2YgcmVzZXJ2aW5nIGEgcmVxdWVzdCBpcyBtb3JlIG9yIGxlc3MNCnRo -YW4gMSUuDQoNCkJhcnQu +On Tue, 2017-09-05 at 00:08 +0800, Ming Lei wrote: +> On Mon, Sep 04, 2017 at 03:40:35PM +0000, Bart Van Assche wrote: +> > Have you considered to use the blk-mq "reserved request" mechanism to avoid +> > starvation of power management requests instead of making the block layer +> > even more complicated than it already is? +> +> reserved request is really a bad idea, that means the reserved request +> can't be used for normal I/O, we all know the request/tag space is +> precious, and some device has a quite small tag space, such as sata. +> This way will affect performance definitely. + +Sorry but I'm neither convinced that reserving a request for power management +would be a bad idea nor that it would have a significant performance impact nor +that it would be complicated to implement. Have you noticed that the Linux ATA +implementation already reserves a request for internal use and thereby reduces +the queue depth from 32 to 31 (see also ATA_TAG_INTERNAL)? What I would like to +know if is whether the performance impact of reserving a request is more or less +than 1%. + +Bart. diff --git a/a/content_digest b/N1/content_digest index 3886638..dbd4901 100644 --- a/a/content_digest +++ b/N1/content_digest @@ -20,25 +20,25 @@ " tj@kernel.org <tj@kernel.org>\0" "\00:1\0" "b\0" - "T24gVHVlLCAyMDE3LTA5LTA1IGF0IDAwOjA4ICswODAwLCBNaW5nIExlaSB3cm90ZToNCj4gT24g\n" - "TW9uLCBTZXAgMDQsIDIwMTcgYXQgMDM6NDA6MzVQTSArMDAwMCwgQmFydCBWYW4gQXNzY2hlIHdy\n" - "b3RlOg0KPiA+IEhhdmUgeW91IGNvbnNpZGVyZWQgdG8gdXNlIHRoZSBibGstbXEgInJlc2VydmVk\n" - "IHJlcXVlc3QiIG1lY2hhbmlzbSB0byBhdm9pZA0KPiA+IHN0YXJ2YXRpb24gb2YgcG93ZXIgbWFu\n" - "YWdlbWVudCByZXF1ZXN0cyBpbnN0ZWFkIG9mIG1ha2luZyB0aGUgYmxvY2sgbGF5ZXINCj4gPiBl\n" - "dmVuIG1vcmUgY29tcGxpY2F0ZWQgdGhhbiBpdCBhbHJlYWR5IGlzPw0KPiANCj4gcmVzZXJ2ZWQg\n" - "cmVxdWVzdCBpcyByZWFsbHkgYSBiYWQgaWRlYSwgdGhhdCBtZWFucyB0aGUgcmVzZXJ2ZWQgcmVx\n" - "dWVzdA0KPiBjYW4ndCBiZSB1c2VkIGZvciBub3JtYWwgSS9PLCB3ZSBhbGwga25vdyB0aGUgcmVx\n" - "dWVzdC90YWcgc3BhY2UgaXMNCj4gcHJlY2lvdXMsIGFuZCBzb21lIGRldmljZSBoYXMgYSBxdWl0\n" - "ZSBzbWFsbCB0YWcgc3BhY2UsIHN1Y2ggYXMgc2F0YS4NCj4gVGhpcyB3YXkgd2lsbCBhZmZlY3Qg\n" - "cGVyZm9ybWFuY2UgZGVmaW5pdGVseS4NCg0KU29ycnkgYnV0IEknbSBuZWl0aGVyIGNvbnZpbmNl\n" - "ZCB0aGF0IHJlc2VydmluZyBhIHJlcXVlc3QgZm9yIHBvd2VyIG1hbmFnZW1lbnQgDQp3b3VsZCBi\n" - "ZSBhIGJhZCBpZGVhIG5vciB0aGF0IGl0IHdvdWxkIGhhdmUgYSBzaWduaWZpY2FudCBwZXJmb3Jt\n" - "YW5jZSBpbXBhY3Qgbm9yDQp0aGF0IGl0IHdvdWxkIGJlIGNvbXBsaWNhdGVkIHRvIGltcGxlbWVu\n" - "dC4gSGF2ZSB5b3Ugbm90aWNlZCB0aGF0IHRoZSBMaW51eCBBVEENCmltcGxlbWVudGF0aW9uIGFs\n" - "cmVhZHkgcmVzZXJ2ZXMgYSByZXF1ZXN0IGZvciBpbnRlcm5hbCB1c2UgYW5kIHRoZXJlYnkgcmVk\n" - "dWNlcw0KdGhlIHF1ZXVlIGRlcHRoIGZyb20gMzIgdG8gMzEgKHNlZSBhbHNvIEFUQV9UQUdfSU5U\n" - "RVJOQUwpPyBXaGF0IEkgd291bGQgbGlrZSB0bw0Ka25vdyBpZiBpcyB3aGV0aGVyIHRoZSBwZXJm\n" - "b3JtYW5jZSBpbXBhY3Qgb2YgcmVzZXJ2aW5nIGEgcmVxdWVzdCBpcyBtb3JlIG9yIGxlc3MNCnRo\n" - YW4gMSUuDQoNCkJhcnQu + "On Tue, 2017-09-05 at 00:08 +0800, Ming Lei wrote:\n" + "> On Mon, Sep 04, 2017 at 03:40:35PM +0000, Bart Van Assche wrote:\n" + "> > Have you considered to use the blk-mq \"reserved request\" mechanism to avoid\n" + "> > starvation of power management requests instead of making the block layer\n" + "> > even more complicated than it already is?\n" + "> \n" + "> reserved request is really a bad idea, that means the reserved request\n" + "> can't be used for normal I/O, we all know the request/tag space is\n" + "> precious, and some device has a quite small tag space, such as sata.\n" + "> This way will affect performance definitely.\n" + "\n" + "Sorry but I'm neither convinced that reserving a request for power management \n" + "would be a bad idea nor that it would have a significant performance impact nor\n" + "that it would be complicated to implement. Have you noticed that the Linux ATA\n" + "implementation already reserves a request for internal use and thereby reduces\n" + "the queue depth from 32 to 31 (see also ATA_TAG_INTERNAL)? What I would like to\n" + "know if is whether the performance impact of reserving a request is more or less\n" + "than 1%.\n" + "\n" + Bart. -ca61b0a827195c636628ffc011db12051601cff5eb0a692656a4ec308d46e7b7 +14acf8dac66c04e347c1a2770d29186751d363d1229efe2d38805c3d298c0915
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