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Date: Mon, 22 Nov 2010 13:23:25 +0100 From: Christoph Bartoschek <bartoschek@...uni-bonn.de> To: linux-ext4@...r.kernel.org Subject: ext4_alloc_context occupies 150 GiB of memory and makes the system unusable Hi, I have the problem that on one machine lots of memory is allocated for ext4_alloc_context. I would like to know for what purpose the memory is allocated and why it is not given to processes that need memory. The machine normally only uses a local ext4 for booting. The data it is working on comes from NFS. Now there are several normally CPU-bound jobs running but they only get 1-2% of cputime because they are constantly swapping. They are swapping because of the 192 GiB the machine has 150 GiB are allocated for ext4_alloc_context. Here is the output of /dev/meminfo: MemTotal: 198493288 kB MemFree: 853372 kB Buffers: 824 kB Cached: 26108 kB SwapCached: 6369336 kB Active: 37073576 kB Inactive: 1104932 kB Active(anon): 37059712 kB Inactive(anon): 1090980 kB Active(file): 13864 kB Inactive(file): 13952 kB Unevictable: 0 kB Mlocked: 0 kB SwapTotal: 209713148 kB SwapFree: 149362056 kB Dirty: 16 kB Writeback: 0 kB AnonPages: 37642012 kB Mapped: 13312 kB Shmem: 0 kB Slab: 158765316 kB SReclaimable: 158732380 kB SUnreclaim: 32936 kB KernelStack: 2968 kB PageTables: 202500 kB NFS_Unstable: 4 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 308959792 kB Committed_AS: 64376360 kB VmallocTotal: 34359738367 kB VmallocUsed: 736572 kB VmallocChunk: 34358994676 kB We see that Slab uses most of the memory. And within slab nearly everything is used for ext4_alloc_context. There is the output of slabtop: Active / Total Objects (% used) : 364597 / 1070670469 (0.0%) Active / Total Slabs (% used) : 52397 / 39688960 (0.1%) Active / Total Caches (% used) : 107 / 193 (55.4%) Active / Total Size (% used) : 159579.25K / 150697605.41K (0.1%) Minimum / Average / Maximum Object : 0.02K / 0.14K / 4096.00K OBJS ACTIVE USE OBJ SIZE SLABS OBJ/SLAB CACHE SIZE NAME 1070187012 0 0% 0.14K 39636556 27 158546224K ext4_alloc_context I see no reason why ext4 should use so much memory. What is it used for? And how can I release it to get it used for my processes. The overall system is very sluggish now. Here is top info for some computing jobs: top - 13:06:06 up 10 days, 22:04, 5 users, load average: 9.65, 9.74, 9.80 Tasks: 272 total, 1 running, 271 sleeping, 0 stopped, 0 zombie Cpu(s): 0.4%us, 0.3%sy, 0.0%ni, 46.5%id, 52.8%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 193841M total, 192945M used, 895M free, 0M buffers Swap: 204797M total, 61718M used, 143079M free, 163113M cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 19459 joachimi 20 0 23.6g 11g 4000 D 0 6.1 417:07.29 bonnRoute 9329 bartosch 20 0 11.7g 9g 3436 D 0 5.3 38:55.70 chipbench 28845 bartosch 20 0 10.9g 5.0g 1028 D 0 2.6 28:27.45 chipbench 6505 bartosch 20 0 10.7g 2.8g 976 D 0 1.5 289:24.73 chipbench 11061 bartosch 20 0 9.8g 1.5g 900 D 1 0.8 146:07.40 chipbench 11010 bartosch 20 0 5638m 1.5g 2800 D 0 0.8 82:48.69 chipbench 10946 bartosch 20 0 5952m 1.3g 936 D 0 0.7 80:57.63 chipbench 10976 bartosch 20 0 5563m 1.3g 936 D 1 0.7 77:53.40 chipbench 11030 bartosch 20 0 9807m 1.2g 4272 D 0 0.6 149:40.97 chipbench 9330 bartosch 20 0 69572 7160 376 S 0 0.0 0:33.06 chipbench 10914 bartosch 20 0 81888 4668 480 S 0 0.0 0:48.84 chipbench 17065 bartosch 20 0 99.0m 3408 488 S 0 0.0 0:41.91 chipbench 11031 bartosch 20 0 75724 2988 496 S 0 0.0 0:53.41 chipbench iotop shows that the jobs while not creating any normal I/O create lots of disk reads and spents nearly 100% for swapping: Total DISK READ: 4.91 M/s | Total DISK WRITE: 0 B/s PID USER DISK READ DISK WRITE SWAPIN IO> COMMAND 79 root 0 B/s 0 B/s 0.00 % 94.34 % [kswapd0] 10946 bartosch 3.14 M/s 0 B/s 65.42 % 1.54 % chipbench 28845 bartosch 334.16 K/s 0 B/s 99.99 % 0.00 % chipbench 6505 bartosch 194.28 K/s 0 B/s 99.99 % 0.00 % chipbench 10976 bartosch 147.65 K/s 0 B/s 99.99 % 0.00 % chipbench 11010 bartosch 170.97 K/s 0 B/s 95.03 % 0.00 % chipbench 11030 bartosch 85.48 K/s 0 B/s 77.11 % 0.00 % chipbench 11061 bartosch 174.85 K/s 0 B/s 99.00 % 0.00 % chipbench 19459 joachimi 155.42 K/s 0 B/s 83.84 % 0.00 % bonnRoute 9329 bartosch 551.75 K/s 0 B/s 99.99 % 0.00 % chipbench The problem appeared about after a week of uptime. The system is opensuse 11.3: Linux euler 2.6.34.7-0.5-desktop #1 SMP PREEMPT 2010-10-25 08:40:12 +0200 x86_64 x86_64 x86_64 GNU/Linux I would like to prevent a reboot. Thanks Christoph -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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