On Wed, Dec 13, 2017 at 5:57 PM, Masahiko Sawada <sawada.m...@gmail.com> wrote: > On Wed, Dec 13, 2017 at 4:30 PM, Andres Freund <and...@anarazel.de> wrote: >> On 2017-12-13 16:02:45 +0900, Masahiko Sawada wrote: >>> When we add extra blocks on a relation do we access to the disk? I >>> guess we just call lseek and write and don't access to the disk. If so >>> the performance degradation regression might not be much. >> >> Usually changes in the file size require the filesystem to perform >> metadata operations, which in turn requires journaling on most >> FSs. Which'll often result in synchronous disk writes. >> > > Thank you. I understood the reason why this measurement should use two > different filesystems. >
Here is the result. I've measured the through-put with some cases on my virtual machine. Each client loads 48k file to each different relations located on either xfs filesystem or ext4 filesystem, for 30 sec. Case 1: COPYs to relations on different filessystems(xfs and ext4) and N_RELEXTLOCK_ENTS is 1024 clients = 2, avg = 296.2068 clients = 5, avg = 372.0707 clients = 10, avg = 389.8850 clients = 50, avg = 428.8050 Case 2: COPYs to relations on different filessystems(xfs and ext4) and N_RELEXTLOCK_ENTS is 1 clients = 2, avg = 294.3633 clients = 5, avg = 358.9364 clients = 10, avg = 383.6945 clients = 50, avg = 424.3687 And the result of current HEAD is following. clients = 2, avg = 284.9976 clients = 5, avg = 356.1726 clients = 10, avg = 375.9856 clients = 50, avg = 429.5745 In case2, the through-put got decreased compare to case 1 but it seems to be almost same as current HEAD. Because the speed of acquiring and releasing extension lock got x10 faster than current HEAD as I mentioned before, the performance degradation may not have gotten decreased than I expected even in case 2. Since my machine doesn't have enough resources the result of clients = 50 might not be a valid result. Regards, -- Masahiko Sawada NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center
