Messages in this thread Patch in this message | | | Date | Tue, 05 Oct 2004 22:36:25 +0900 | From | Hideo AOKI <> | Subject | [PATCH 2.6] vm-thrashing-control-tuning |
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Hello,
Token based thrashing control has a good effect in thrashing situation. In current implementation, token timeout is a fixed value as SWAP_TOKEN_TIMEOUT. I think that administrators can improve thrashing behavior if the value can be changed.
This patch adds "swap_token_timeout" parameter in /proc/sys/vm. The parameter means expired time of token. Unit of the value is HZ, and the default value is the same as current SWAP_TOKEN_TIMEOUT (i.e. HZ * 300). The patch can be applied to both 2.6.9-rc2 and 2.6.9-rc3.
I tested the patch on an IA-32 4 way machine which has 4GB memory. Based kernel was 2.6.9-rc1. I tested five swap_token_time_out values. I created 256 workload generation processes on the machine. Each process generated same workload: repeating random file writing and memory access (Memory region is 18MB). I ran the processes for one hour and calculated write throughput of workload processes. The result was following.
swap_token_time_out Write throughput [MB/s] ------------------- ---------------------- 30,000,000 6.71 3,000,000 8.26 300,000 (DEFAULT) 7.90 30,000 8.16 3,000 7.43
As you can see, it may be possible to improve application performance according to tune swap_token_time_out. Additionally, I think it is better to decrease default value. One reason is that the other values gained good performance. The other is that behavior of kernel may be unstable if swap_token_time_out is too long.
I am exploring tuning policy.
Any comments or suggestions?
Best regards,
Hideo AOKI
Systems Development Laboratory, Hitachi, Ltd.
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Signed-off-by: Hideo Aoki <aoki@sdl.hitachi.co.jp>
diff -uprN linux-2.6.9-rc2/include/linux/swap.h linux-2.6.9-rc2-tbtc_tune/include/linux/swap.h --- linux-2.6.9-rc2/include/linux/swap.h 2004-09-15 12:20:40.000000000 +0900 +++ linux-2.6.9-rc2-tbtc_tune/include/linux/swap.h 2004-09-28 15:12:33.000000000 +0900 @@ -230,6 +230,7 @@ extern spinlock_t swaplock;
/* linux/mm/thrash.c */ extern struct mm_struct * swap_token_mm; +extern unsigned long swap_token_default_timeout; extern void grab_swap_token(void); extern void __put_swap_token(struct mm_struct *);
diff -uprN linux-2.6.9-rc2/include/linux/sysctl.h linux-2.6.9-rc2-tbtc_tune/include/linux/sysctl.h --- linux-2.6.9-rc2/include/linux/sysctl.h 2004-09-15 12:20:40.000000000 +0900 +++ linux-2.6.9-rc2-tbtc_tune/include/linux/sysctl.h 2004-09-28 15:12:33.000000000 +0900 @@ -167,6 +167,7 @@ enum VM_HUGETLB_GROUP=25, /* permitted hugetlb group */ VM_VFS_CACHE_PRESSURE=26, /* dcache/icache reclaim pressure */ VM_LEGACY_VA_LAYOUT=27, /* legacy/compatibility virtual address space layout */ + VM_SWAP_TOKEN_TIMEOUT=28 /* default time for token time out */ };
diff -uprN linux-2.6.9-rc2/kernel/sysctl.c linux-2.6.9-rc2-tbtc_tune/kernel/sysctl.c --- linux-2.6.9-rc2/kernel/sysctl.c 2004-09-15 12:20:41.000000000 +0900 +++ linux-2.6.9-rc2-tbtc_tune/kernel/sysctl.c 2004-09-28 15:12:33.000000000 +0900 @@ -800,6 +800,15 @@ static ctl_table vm_table[] = { .extra1 = &zero, }, #endif + { + .ctl_name = VM_SWAP_TOKEN_TIMEOUT, + .procname = "swap_token_timeout", + .data = &swap_token_default_timeout, + .maxlen = sizeof(swap_token_default_timeout), + .mode = 0644, + .proc_handler = &proc_dointvec, + .strategy = &sysctl_intvec, + }, { .ctl_name = 0 } };
diff -uprN linux-2.6.9-rc2/mm/thrash.c linux-2.6.9-rc2-tbtc_tune/mm/thrash.c --- linux-2.6.9-rc2/mm/thrash.c 2004-09-15 12:20:42.000000000 +0900 +++ linux-2.6.9-rc2-tbtc_tune/mm/thrash.c 2004-09-28 15:12:33.000000000 +0900 @@ -20,6 +20,8 @@ struct mm_struct * swap_token_mm = &init
#define SWAP_TOKEN_CHECK_INTERVAL (HZ * 2) #define SWAP_TOKEN_TIMEOUT (HZ * 300) +unsigned long swap_token_default_timeout = SWAP_TOKEN_TIMEOUT; +
/* * Take the token away if the process had no page faults @@ -75,10 +77,10 @@ void grab_swap_token(void) if ((reason = should_release_swap_token(mm))) { unsigned long eligible = jiffies; if (reason == SWAP_TOKEN_TIMED_OUT) { - eligible += SWAP_TOKEN_TIMEOUT; + eligible += swap_token_default_timeout; } mm->swap_token_time = eligible; - swap_token_timeout = jiffies + SWAP_TOKEN_TIMEOUT; + swap_token_timeout = jiffies + swap_token_default_timeout; swap_token_mm = current->mm; } spin_unlock(&swap_token_lock);
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