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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20201002170124.20D8.409509F4@e16-tech.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="dD4gNQV49gDGnZ50phV4iVGu9U59z99Eq" X-Provags-ID: V03:K1:3+Pw1q6eXDSj39+H8fV8lNmF+qfd8TUMQTA/rjZouO6mukkAr4Y 8mOwLp2MW3ZNZ9SI4PLLEee34iBXbSk5cyE64uMhGyVqIXvzSHJLpq4Zn2niSILIKSVqhUR A8B6PmvT5BULGwiBkY9An/3sX+mP24aX7rZHRmuavumzFWCvrMUoqmufXBiZWlK8PR5y5Zq z2+HYO2iggj286ZrFOqLA== X-UI-Out-Filterresults: notjunk:1;V03:K0:8mua7YBjlIw=:lsj5UWlKmZsDFvbbsYnvsh BEdqepKEbKn/PR6pJddL6iRMeYF6jgQmjF2MO8XKF2aSpi2uEDasxD/ByE/yDwVgF16A9mc21 uJg0U6RCf8JF2SIVKHn4QXEwzgdrYoLygQg3tcgNIVNofTS7+fIPJEyCoOWOG/ji494Thz1bE plb8UThe+K6rVeT6t0md6E8TpHTaWcJRKmIvDgn7h3j50y1asNjf/EVaCkKKed4qPUGrJ2gXa 6cwAkIJCGbckqj9eVZCEr5jvg9hbL9MwgRaCTLpaTiiB+NQrPVF8FMOsisXRozvJNmfDm7XQi 6W78hChUrv3mQZVdsowHa/QEeL3s0yj9CyLXNNFnBXaT/p8Pg2J+CY1QKTNOIVxcVXHYvVhsK ntN1LzerfB/c0X20tAev5AUUZj9qRkA9xm8MKzrvfkQAwwUIr5Cl9Efxs/D3Ht+dxY8S6ssy3 BCDHzxJas0sl4hS4yeAWihsPSUrkFSRiCfiRH66NPOXWT6fm0Nk3nSEdFc6eAN154YkOY3CoI Q3u5uTCFpQAyE6yQhiS+gaieSK49lOX9qP7V+ihAJ10rWwARHaT+I3MS7ruWLgQQd5Whyx+Xi XQUADABE2wh+s1iUq2Oj+ejtILH7nMLFleE0oxymMx+r3gfJE+2ESDZaiOXOvWUqV1sGvq6OZ +tQ81lHOIafS/5q5Wg89fd6cOW9mYBFOs/uUOG7q/EjmXLi5G0fh+Bz4ErlKE/XZEj75CP1yD z7yjsZl1pU/07bZybL8pYnJDOdBzKS2ZH/p40idnGu5+tAf1etn5qdeY0sH43adXdcy1NiRr9 HkyeSGn/Qv+Gw6uCuJR57vPhrmPkIy4RiTsdgnxTyslbFTTKN4bU3d1gDmrjoH0ohTWyQX6OI wfT+WciqLwrd3tbc/AP4APXd5Tepn+rhm0VBTJuIEP6oFt1CzZk8u7cJIQYXTH1Eq+VYJ0ecm 7kSt7Ioz+pWLtwVKMD6gBDKa8Yqs3erD/zZgF10kRLs4UpWo6j1/zk396cBnwWzPsdJm55To1 rD+hv+Gx2xdgRxEfHFgstsLjLeoq+PIso7DB2oao1WnO+XIriSZAHEqEQERj2oW2uffRtC6c0 UunUxBhQlwV0PlhwbdQcBWtWlcVNJLNHluk4Lh619fdia4QqbQTT67/cjLFJXNIdzXYhZ/e0/ oHgwWgahFz/qotGw/upyEZaWiZmo4OkhnzHxrSTciiUPy3yddT7KSE3ih9wN39NyiAjgAg8LU 7kZwWgrW1sEa6n7ucux47njdDJuHRACrjohlSsA== Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --dD4gNQV49gDGnZ50phV4iVGu9U59z99Eq Content-Type: multipart/mixed; boundary="Zh7k0i1EPKTysHqhhZdxYNgowUmcMSFCs" --Zh7k0i1EPKTysHqhhZdxYNgowUmcMSFCs Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 2020/10/2 =E4=B8=8B=E5=8D=885:01, Wang Yugui wrote: > Hi, >=20 > We have another user case difficult to process. >=20 > Use case:=20 > Add 10T disk * 4 to near full full RAID10 10T *4; > free space maybe be such as 10T,10T,10T,10T,2G,2G,2G,2G. >=20 > There maybe a lot of iterations for this case because of 2G chunk size,= > and then result in bad performance? For that case, it won't. Just 2 runs. The first run, we choose to use 2G as stripe length, it results the last 4 devices to be exhausted. Then in the 2nd run, we use the remaining (10T-2G) as stripe size, and exhaust all devices. Thanks, Qu >=20 > Best Regards > =E7=8E=8B=E7=8E=89=E8=B4=B5 > 2020/10/02 >=20 >> >> >> On 2020/10/2 =E4=B8=8A=E5=8D=889:59, Wang Yugui wrote: >>> Hi, >>> >>> >>>>> such as >>>>> 1) RAID10 with 8T,1T,1T,1T,1T >>>>> the virtal chunk size of 1st iteration: 1T or 0.33T? >>>>> 1T chunk will use 4T at most >>>>> 0.33T chunk will use 5.33T at most? >>>> >>>> You didn't get the point. >>>> For the each loop we: >>>> - Sort the devices with their free space. >>>> In this case, it's 8, 1, 1, 1, 1. >>>> >>>> - Round down to dev increament >>>> Then we got 8, 1, 1, 1. >>>> >>>> - Then allocate chunk >>>> Since the biggest unallocated space is 1T, we allocate a RAID10 wi= th >>>> 1T stripe size, which will be a 2T chunk. >>>> >>>> The remaining size is 7, 0, 0, 0, 1. >>> >>> That is the problem. 1T chunk size is too big for this case. >>> >>> if we use 1/3T chunk size, the result will be same as 1G chunk size. >>> >>> 1st: 8T - 1/3T 2/3T, 2/3T, 2/3T, 1T >>> 2nd: 8T -2/3T 2/3T, 1/3T, 1/3T, 2/3T >>> 3rd: 8T -1T 1/3T, 1/3T, 0T, 1/3T >>> 4th: 8T -4/3T 0T, 0T, 0T, 0T >> >> You're right, smaller balloon chunk size would make the allocation mor= e >> accurate to real chunk allocator. >> >> However that would slow down the calculation, don't forget that we nee= d >> to run that calculation on each chunk allocation. >> Changing the balloon chunk allocation size dynamically may improve thi= s. >> >> But please also keep in mind that, with less and less space left, our >> predication will be more and more accurate, and under estimate is alwa= ys >> less a problem. >> >> So I'll keep your suggestion for future enhancement. >> >> Thanks for pointing out the pitfall of current calculation, >> Qu >> >>> >>> Best Regards >>> =E7=8E=8B=E7=8E=89=E8=B4=B5 >>> 2020/10/02 >>> >>>> >>>> - We go to next round. >>>> No way to allocate new chunk. >>>> >>>> In this case, we can only get 2T chunk. >>>> Just as the chunk allocator do. >>>> >>>>> >>>>> 2) RAID10 with 8T,1T,1T,1T,0.5T >>>>> the virtal chunk size of 1st iteration:0.5T or smaller? >>>> >>>> Still the same, 2T chunk can be allocated using the largest 4 device= s. >>>> >>>> Thanks, >>>> Qu >>>> >>>>> >>>>> Best Regards >>>>> =E7=8E=8B=E7=8E=89=E8=B4=B5 >>>>> 2020/10/02 >>>>> >>>>> >>>>> -------------------------------------- >>>>> =E5=8C=97=E4=BA=AC=E4=BA=AC=E5=9E=93=E7=A7=91=E6=8A=80=E6=9C=89=E9=99= =90=E5=85=AC=E5=8F=B8 >>>>> =E7=8E=8B=E7=8E=89=E8=B4=B5 wangyugui@e16-tech.com >>>>> =E7=94=B5=E8=AF=9D=EF=BC=9A+86-136-71123776 >>>>> >>>> >>> >>> -------------------------------------- >>> =E5=8C=97=E4=BA=AC=E4=BA=AC=E5=9E=93=E7=A7=91=E6=8A=80=E6=9C=89=E9=99= =90=E5=85=AC=E5=8F=B8 >>> =E7=8E=8B=E7=8E=89=E8=B4=B5 wangyugui@e16-tech.com >>> =E7=94=B5=E8=AF=9D=EF=BC=9A+86-136-71123776 >>> >> >=20 > -------------------------------------- > =E5=8C=97=E4=BA=AC=E4=BA=AC=E5=9E=93=E7=A7=91=E6=8A=80=E6=9C=89=E9=99=90= =E5=85=AC=E5=8F=B8 > =E7=8E=8B=E7=8E=89=E8=B4=B5 wangyugui@e16-tech.com > =E7=94=B5=E8=AF=9D=EF=BC=9A+86-136-71123776 >=20 --Zh7k0i1EPKTysHqhhZdxYNgowUmcMSFCs-- --dD4gNQV49gDGnZ50phV4iVGu9U59z99Eq Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEELd9y5aWlW6idqkLhwj2R86El/qgFAl9278gACgkQwj2R86El /qgFXAf/a6RrrHrRiC6fEHQQBONBiACNEvCKDZRoAmB5ejsGtg2snorC7q1YIAN/ l+/XdrirJjMZrKqavo5aHveZ74IZDUCLCIaESofNZL8MmvOGX69g6KoIrwY5nHa0 00O8kEMHTPY1zXmP/R/KR+O+ratqr3D3BhbxDmjpOpKLa527/mNMT+z3A3n8P7km tBsOfJ9cU428RP6wmppLAVQ88Kv5rEMwp277pTQOhIqY/hwcV/kGIAwKqSkhv18I a63+eAyN1qJTG0d/G+81uMZ6rB+1MnvGyHp+zK8fiCewRQjylDm+MsW/6DKajjA+ umjO0M4oIozWIvc/KeEfAR4ViBbIwg== =bpeI -----END PGP SIGNATURE----- --dD4gNQV49gDGnZ50phV4iVGu9U59z99Eq--