From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Examining the Performance and Cost of Revesemaps on 2.5.26 Under Heavy DB Workload Message-ID: From: "Peter Wong" Date: Tue, 17 Sep 2002 13:30:42 -0500 MIME-Version: 1.0 Content-type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org Return-Path: To: linux-mm@kvack.org, lse-tech@lists.sourceforge.net Cc: riel@nl.linux.org, akpm@zip.com.au, mjbligh@us.ibm.com, wli@holomorphy.com, dmccr@us.ibm.comgh@us.ibm.com, Bill Hartner , Troy C Wilson List-ID: I measured a decision support workload using two 2.5.26-based kernels, one of which does NOT have the rmap rollup patch while the other HAS. The database size is 100GB. The 2.5.26 rmap rollup patch was created by Dave McCracken. Based upon the throughput rate and CPU utilization, the two kernels achieve similar performance. Based upon /proc/meminfo, the maximum reversemap size is 22,817,885. Based upon /proc/slabinfo, the maximum number of active pte_chain objects is 3,411,018 with 32 bytes each. It consumes about 104 MB. The maximum number of slabs allocated for pte_chains is 30,186 with 4KB each, corresponding to about 118 MB. Similar memory consumption for rmaps is observed while running the same workload and using Andrew Morton's mm2 patch under 2.5.32. Andrew's patch can be found at http://www.zip.com.au/~akpm/linux/patches/2.5/2.5.32/2.5.32-mm2/. Note that since readv is not available on 2.5.26, the runs above used "read" instead of "readv". My previous note (Sept. 10, 2002) indicated that the memory consumption for rmaps under 2.5.32 using "readv" is about 223 MB. And "readv" is the preferred method for this workload. The difference of memory consumption by using read (118 MB) and readv (223 MB) is likely due to the different I/O algorithms used by the DBMS. When there are multiple instances of this workload running concurrently, the amount of memory allocated to rmaps is even more significant. More data will be provided later. ---------------------------------------------------------------------- System Information: - 8-way 700MHz Pentium III Xeon processors, 2MB L2 Cache - 4GB RAM - 6 SCSI controllers connected to 120 9.1 GB disks with 10K RPM ---------------------------------------------------------------------- Regards, Peter Peter Wai Yee Wong IBM Linux Technology Center, Performance Analysis email: wpeter@us.ibm.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/