Date: Thu, 6 Feb 2014 15:44:28 +0100 (CET) From: krichy@tvnetwork.hu To: Richard Kojedzinszky <krichy@cflinux.hu> Cc: freebsd-fs@freebsd.org Subject: Re: geom write cache handling Message-ID: <alpine.DEB.2.10.1402061543280.18231@krichy.tvnetwork.hu> In-Reply-To: <alpine.BSF.2.00.1402061528170.61272@pi.nmdps.net> References: <alpine.BSF.2.00.1402061528170.61272@pi.nmdps.net>
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This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --1030603365-1547680064-1391697868=:18231 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Fortunately I have my drives attached to a SAS controller, so I could add quirks for them. They are also attached. Regards, Kojedzinszky Richard Euronet Magyarorszag Informatika Zrt. On Thu, 6 Feb 2014, Richard Kojedzinszky wrote: > Date: Thu, 6 Feb 2014 15:36:54 +0100 (CET) > From: Richard Kojedzinszky <krichy@cflinux.hu> > To: freebsd-fs@freebsd.org > Subject: geom write cache handling > > Dear fs team, > > I own an STEC SSD, which I use for ZFS SLOG. The device is broken in that if > it gets a SCSI synchronize cache, it does something which is very slow. > Actually with it in FreeBSD the reachable sync IOPS is around 100. When the > device has write cache disabled, there is no need to send the SCSI > synchronize cache commands to it, and without them I can reach 1400 IOPS. The > device itself have power-loss-protection, so I risk no data corruption at > all. > > By the way, linux behave the same, if either ata or scsi disks have their > write cache turned off, it even does not send the command to the drive. > > Also, I have an Intel S3700, which is much faster, but have similar symptons. > The drive handles synchronize cache commands much faster than STEC, maybe it > is implemented in the drive as a simple NOP, but as for 4K sync writes a sync > cache follows, it effectively halves the IOPS. I have it attached to a SATA2 > controller only, and with WCE disabled, and sending the sync cache to it I > can reach around 4500 IOPS, while disabling the sync cache it can reach >9000 > IOPS. > > I've attached a very simple patch for the ata layer, but I dont know how to > implement it for the scsi subsystem also. > > Regards, > > Kojedzinszky Richard --1030603365-1547680064-1391697868=:18231 Content-Type: TEXT/x-diff; name=s3700.patch Content-Transfer-Encoding: BASE64 Content-ID: <alpine.DEB.2.10.1402061544281.18231@krichy.tvnetwork.hu> Content-Description: Content-Disposition: attachment; filename=s3700.patch Y29tbWl0IDA4NDFhYzFjZjM1Mzk3MTgxZGI5OGRmOTU0MDE1NDA5NzM1ZjFm YzQNCkF1dGhvcjogQ2hhcmxpZSBSb290IDxyb290QHBpLm5tZHBzLm5ldD4N CkRhdGU6ICAgVGh1IEZlYiA2IDE0OjQyOjIwIDIwMTQgKzAxMDANCg0KICAg IEludGVsIFMzNzAwIFNTRCBxdWlya3MNCg0KZGlmZiAtLWdpdCBhL3N5cy9j YW0vc2NzaS9zY3NpX2RhLmMgYi9zeXMvY2FtL3Njc2kvc2NzaV9kYS5jDQpp bmRleCBjYjVkNDFmLi45M2JiMjMxIDEwMDY0NA0KLS0tIGEvc3lzL2NhbS9z Y3NpL3Njc2lfZGEuYw0KKysrIGIvc3lzL2NhbS9zY3NpL3Njc2lfZGEuYw0K QEAgLTk4NCw2ICs5ODQsMTUgQEAgc3RhdGljIHN0cnVjdCBkYV9xdWlya19l bnRyeSBkYV9xdWlya190YWJsZVtdID0NCiAJfSwNCiAJew0KIAkJLyoNCisJ CSAqIEludGVsIFMzNzAwIFNlcmllcyBTU0RzDQorCQkgKiA0ayBvcHRpbWlz ZWQgJiB0cmltIG9ubHkgd29ya3MgaW4gNGsgcmVxdWVzdHMgKyA0ayBhbGln bmVkDQorCQkgKiBjYWNoZSBmbHVzaCBub3QgbmVlZGVkLCBhcyBwb3dlci1s b3NzLXByb3RlY3RlZA0KKwkJICovDQorCQl7IFRfRElSRUNULCBTSVBfTUVE SUFfRklYRUQsICJBVEEiLCAiSU5URUwgU1NEU0MyQkEqIiwgIioiIH0sDQor CQkvKnF1aXJrcyovREFfUV80SyB8IERBX1FfTk9fU1lOQ19DQUNIRQ0KKwl9 LA0KKwl7DQorCQkvKg0KIAkJICogS2luZ3N0b24gRTEwMCBTZXJpZXMgU1NE cw0KIAkJICogNGsgb3B0aW1pc2VkICYgdHJpbSBvbmx5IHdvcmtzIGluIDRr IHJlcXVlc3RzICsgNGsgYWxpZ25lZA0KIAkJICovDQo= --1030603365-1547680064-1391697868=:18231 Content-Type: TEXT/x-diff; name=stec.patch Content-Transfer-Encoding: BASE64 Content-ID: <alpine.DEB.2.10.1402061544282.18231@krichy.tvnetwork.hu> Content-Description: Content-Disposition: attachment; filename=stec.patch Y29tbWl0IDcxNmNjZjBiMDMwNTA0ZTM5YWM2MGMyNGIxYWFlZDkxOTliZTEx M2YNCkF1dGhvcjogQ2hhcmxpZSBSb290IDxyb290QHBpLm5tZHBzLm5ldD4N CkRhdGU6ICAgV2VkIEphbiAxNSAyMTo1MDo0NCAyMDE0ICswMTAwDQoNCiAg ICBBZGRlZCBubyBzeW5jIGNhY2hlIHF1aXJrIGZvciBTVEVDIE1BQ0gxNiBk cml2ZXMNCg0KZGlmZiAtLWdpdCBhL3N5cy9jYW0vc2NzaS9zY3NpX2RhLmMg Yi9zeXMvY2FtL3Njc2kvc2NzaV9kYS5jDQppbmRleCA0YTk2OTgxLi5jYjVk NDFmIDEwMDY0NA0KLS0tIGEvc3lzL2NhbS9zY3NpL3Njc2lfZGEuYw0KKysr IGIvc3lzL2NhbS9zY3NpL3Njc2lfZGEuYw0KQEAgLTEwNjIsNiArMTA2Miwx NCBAQCBzdGF0aWMgc3RydWN0IGRhX3F1aXJrX2VudHJ5IGRhX3F1aXJrX3Rh YmxlW10gPQ0KIAkJeyBUX0RJUkVDVCwgU0lQX01FRElBX0ZJWEVELCAiQVRB IiwgIlNHOVhDUzJEKiIsICIqIiB9LA0KIAkJLypxdWlya3MqL0RBX1FfNEsN CiAJfSwNCisJew0KKwkJLyoNCisJCSAqIFNURUMgTUFDSDE2IFNBVEEgU1NE cw0KKwkJICogTm8gY2FjaGUgc3luYw0KKwkJICovDQorCQl7IFRfRElSRUNU LCBTSVBfTUVESUFfRklYRUQsICJBVEEiLCAiU1RFQyAgICBNQUNIMTYqIiwg IioiIH0sDQorCQkvKnF1aXJrcyovREFfUV9OT19TWU5DX0NBQ0hFDQorCX0s DQogfTsNCiANCiBzdGF0aWMJZGlza19zdHJhdGVneV90CWRhc3RyYXRlZ3k7 DQo= --1030603365-1547680064-1391697868=:18231--
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