Hello Zhou, >On 10/17/2014 11:50 AM, Atsushi Kumagai wrote: >> Hello, >> >> The code looks good to me, thanks Zhou. >> Now, I have a question on performance. >> >>> The issue is discussed at http://lists.infradead.org/pipermail/kexec/2014-March/011289.html >>> >>> This patch implements the idea of 2-pass algorhythm with smaller memory to manage splitblock table. >>> Exactly the algorhythm is still 3-pass,but the time of second pass is much shorter. >>> The tables below show the performence with different size of cyclic-buffer and splitblock. >>> The test is executed on the machine having 128G memory. >>> >>> the value is total time (including first pass and second pass). >>> the value in brackets is the time of second pass. >> >> Do you have any idea why the time of second pass is much larger when >> the splitblock-size is 2G ? I worry about the scalability. >> >Hello, > > Since the previous machine can't be used for some reasons,I test several times using latest code >in others, but that never happened. It seems that all things are right. Tests are executed in two machines(server,pc). >Tests are based on: Well...OK, I'll take that as an issue specific to that machine (or your mistakes as you said). Now I have another question. calculate_end_pfn_by_splitblock(): ... /* deal with incomplete splitblock */ if (pfn_needed_by_per_dumpfile < 0) { --*current_splitblock; splitblock_inner -= splitblock->entry_size; end_pfn = CURRENT_SPLITBLOCK_PFN_NUM; *current_splitblock_pfns = (-1) * pfn_needed_by_per_dumpfile; pfn_needed_by_per_dumpfile += read_value_from_splitblock_table(splitblock_inner); end_pfn = calculate_end_pfn_in_cycle(CURRENT_SPLITBLOCK_PFN_NUM, CURRENT_SPLITBLOCK_PFN_NUM + splitblock->page_per_splitblock, end_pfn,pfn_needed_by_per_dumpfile); } This block causes the re-scanning for the cycle corresponding to the current_splitblock, so the larger cyc-buf, the longer the time takes. If cyc-buf is 4096 (this means the number of cycle is 1), the whole page scanning will be done in the second pass. Actually, the performance when cyc-buf=4096 was so bad. Is this process necessary ? I think splitting splitblocks is overkill because I understood that splblk-size is the granularity of the fairness I/O, tuning splblk-size is a trade off between fairness and memory usage. However, there is no advantage to reducing splblk-size in the current implementation, it just consumes large amounts of memory. If we remove the process, we can avoid the whole page scanning in the second pass and reducing splblk-size will be meaningful as I expected. Thanks Atsushi Kumagai > test1: > machine: server > crashkernel: 512M > vmcore: /proc/vmcore (128G) > > > test2: > machine: pc > crashkernel: 256M > vmcore: vmcore dumped from the server > > test3: > machine: pc > crashkernel: 128M > vmcore: vmcore dumped from the server > > > >test1: > sec > cyc-buf 2 4 8 16 32 64 > splblk-size > 2M 1.53(0.00) 1.24(0.00) 1.08(0.01) 0.99(0.01) 0.95(0.01) 0.95(0.04) > 4M 1.52(0.00) 1.24(0.00) 1.08(0.01) 0.99(0.01) 0.95(0.01) 0.96(0.04) > 8M 1.53(0.00) 1.23(0.00) 1.08(0.01) 0.99(0.01) 0.95(0.01) 0.95(0.04) > 16M 1.53(0.00) 1.24(0.00) 1.08(0.01) 1.00(0.01) 0.94(0.01) 0.96(0.04) > 32M 1.52(0.00) 1.25(0.00) 1.08(0.01) 0.99(0.01) 0.94(0.01) 0.96(0.05) > 64M 1.52(0.00) 1.23(0.00) 1.07(0.01) 0.99(0.01) 0.97(0.01) 0.96(0.05) > 128M 1.54(0.01) 1.25(0.01) 1.08(0.01) 0.99(0.01) 0.96(0.02) 0.96(0.05) > 256M 1.53(0.01) 1.25(0.01) 1.08(0.01) 0.99(0.01) 0.95(0.02) 0.96(0.05) > 512M 1.53(0.01) 1.25(0.01) 1.07(0.01) 1.01(0.02) 0.95(0.02) 0.96(0.05) > 1G 1.54(0.02) 1.25(0.02) 1.08(0.02) 1.00(0.02) 0.96(0.03) 0.97(0.06) > 2G 1.59(0.07) 1.30(0.06) 1.11(0.05) 1.04(0.06) 1.00(0.07) 0.98(0.07) > 4G 1.60(0.08) 1.31(0.07) 1.14(0.07) 1.05(0.07) 1.02(0.08) 1.00(0.08) > 8G 1.60(0.08) 1.31(0.07) 1.14(0.07) 1.05(0.07) 1.02(0.08) 0.99(0.08) > 16G 1.60(0.08) 1.30(0.07) 1.14(0.07) 1.05(0.07) 1.02(0.08) 0.99(0.08) > > cyc-buf 128 256 512 1024 2048 4096 > splblk-size > 2M 0.95(0.04) 0.94(0.04) 0.94(0.04) 0.95(0.05) 0.94(0.05) 1.68(0.78) > 4M 0.95(0.04) 0.94(0.04) 0.94(0.04) 0.95(0.05) 0.94(0.05) 1.67(0.78) > 8M 0.94(0.04) 0.94(0.04) 0.94(0.04) 0.95(0.05) 0.95(0.05) 1.68(0.78) > 16M 0.96(0.05) 0.94(0.04) 0.95(0.05) 0.94(0.04) 0.94(0.05) 1.68(0.78) > 32M 0.95(0.05) 0.94(0.05) 0.94(0.05) 0.94(0.05) 0.94(0.05) 1.68(0.78) > 64M 0.96(0.05) 0.95(0.05) 0.94(0.05) 0.94(0.05) 0.95(0.05) 1.67(0.78) > 128M 0.96(0.05) 0.95(0.05) 0.95(0.05) 0.95(0.05) 0.94(0.05) 1.67(0.78) > 256M 0.95(0.05) 0.95(0.05) 0.95(0.05) 0.94(0.05) 0.94(0.05) 1.67(0.78) > 512M 0.96(0.05) 0.95(0.05) 0.94(0.05) 0.94(0.05) 0.95(0.05) 1.68(0.79) > 1G 0.96(0.06) 0.96(0.06) 0.97(0.06) 0.96(0.06) 0.96(0.07) 1.69(0.80) > 2G 0.97(0.07) 0.97(0.07) 0.97(0.07) 0.96(0.07) 0.96(0.07) 1.70(0.80) > 4G 1.02(0.10) 1.00(0.10) 0.99(0.10) 1.00(0.10) 0.99(0.10) 1.74(0.84) > 8G 1.00(0.10) 1.06(0.16) 1.05(0.16) 1.05(0.16) 1.06(0.16) 1.78(0.89) > 16G 1.00(0.10) 1.06(0.16) 1.16(0.26) 1.16(0.26) 1.15(0.26) 1.90(1.00) > > > > >test2: > sec > cyc-buf 2 4 8 16 32 64 > splblk-size > 2M 23.42(0.03) 23.38(0.05) 23.46(0.11) 23.56(0.17) 23.56(0.23) 23.84(0.48) > 4M 23.35(0.03) 23.35(0.05) 23.56(0.11) 23.51(0.17) 23.60(0.22) 23.81(0.48) > 8M 23.34(0.03) 23.38(0.05) 23.46(0.11) 23.55(0.16) 23.58(0.22) 23.84(0.48) > 16M 23.39(0.03) 23.36(0.06) 23.42(0.11) 23.50(0.16) 23.59(0.23) 23.86(0.48) > 32M 23.43(0.03) 23.38(0.06) 23.47(0.12) 23.54(0.19) 23.58(0.23) 23.89(0.48) > 64M 23.42(0.04) 23.43(0.07) 23.47(0.12) 23.53(0.18) 23.59(0.23) 23.87(0.48) > 128M 23.45(0.07) 23.41(0.09) 23.52(0.14) 23.56(0.19) 23.59(0.23) 23.81(0.48) > 256M 23.47(0.12) 23.48(0.14) 23.50(0.14) 23.55(0.20) 23.62(0.23) 23.84(0.48) > 512M 23.48(0.18) 23.56(0.19) 23.55(0.19) 23.60(0.24) 23.71(0.32) 23.88(0.49) > 1G 23.74(0.30) 23.53(0.23) 23.64(0.31) 23.54(0.24) 23.65(0.27) 23.98(0.52) > 2G 23.78(0.48) 23.82(0.48) 23.84(0.48) 23.83(0.49) 23.89(0.52) 23.84(0.52) > 4G 23.91(0.52) 23.81(0.50) 23.92(0.50) 23.87(0.51) 23.88(0.54) 23.92(0.54) > 8G 23.80(0.50) 23.90(0.52) 23.82(0.49) 23.84(0.51) 23.90(0.54) 23.90(0.54) > 16G 23.85(0.51) 23.86(0.50) 23.85(0.51) 23.87(0.51) 23.95(0.54) 23.88(0.54) > > cyc-buf 128 256 512 1024 2048 4096 > splblk-size > 2M 23.90(0.47) 23.84(0.48) 23.84(0.48) 24.06(0.47) 23.93(0.47) 49.00(25.46) > 4M 23.87(0.48) 23.84(0.48) 23.91(0.48) 23.93(0.47) 23.98(0.47) 49.00(25.46) > 8M 23.80(0.48) 23.81(0.48) 23.95(0.48) 23.95(0.47) 24.03(0.52) 49.05(25.45) > 16M 23.86(0.47) 23.84(0.48) 23.90(0.48) 23.93(0.47) 24.00(0.47) 48.95(25.41) > 32M 23.86(0.48) 23.82(0.48) 23.98(0.54) 23.99(0.47) 23.97(0.47) 49.03(25.47) > 64M 23.83(0.48) 23.79(0.48) 23.89(0.48) 24.02(0.47) 23.93(0.47) 48.96(25.49) > 128M 23.92(0.55) 23.91(0.48) 23.85(0.48) 23.98(0.47) 23.90(0.47) 48.98(25.50) > 256M 23.86(0.48) 23.88(0.48) 24.00(0.48) 24.17(0.47) 23.94(0.47) 49.01(25.50) > 512M 23.85(0.49) 23.89(0.55) 23.93(0.49) 23.91(0.48) 24.01(0.48) 49.12(25.54) > 1G 23.85(0.52) 23.84(0.52) 23.98(0.52) 23.98(0.51) 24.02(0.51) 49.28(25.73) > 2G 23.92(0.52) 23.87(0.52) 23.93(0.52) 24.11(0.52) 24.04(0.52) 49.27(25.77) > 4G 24.24(0.91) 24.31(0.91) 24.29(0.91) 24.37(0.90) 24.37(0.90) 50.01(26.49) > 8G 24.27(0.91) 24.94(1.61) 25.07(1.62) 25.11(1.60) 25.02(1.60) 51.24(27.77) > 16G 24.29(0.91) 24.98(1.63) 29.32(5.85) 29.34(5.83) 29.33(5.83) 53.91(30.43) > > >test3: > sec > cyc-buf 2 4 8 16 32 64 > splblk-size > 2M 23.34(0.03) 23.38(0.05) 23.46(0.11) 23.47(0.16) 23.55(0.22) 23.97(0.65) > 4M 23.38(0.03) 23.41(0.05) 23.46(0.11) 23.47(0.16) 23.56(0.22) 23.99(0.65) > 8M 23.33(0.03) 23.41(0.06) 23.50(0.11) 23.52(0.16) 23.54(0.23) 24.05(0.66) > 16M 23.38(0.03) 23.51(0.14) 23.46(0.12) 23.54(0.16) 23.57(0.23) 23.98(0.65) > 32M 23.34(0.03) 23.37(0.06) 23.47(0.12) 23.53(0.18) 23.56(0.23) 24.06(0.66) > 64M 23.36(0.06) 23.43(0.08) 23.52(0.13) 23.53(0.18) 23.63(0.23) 23.99(0.66) > 128M 23.47(0.07) 23.40(0.09) 23.54(0.15) 23.50(0.19) 23.57(0.23) 24.15(0.74) > 256M 23.48(0.13) 23.52(0.14) 23.50(0.15) 23.54(0.19) 23.56(0.23) 23.98(0.66) > 512M 23.49(0.18) 23.49(0.19) 23.60(0.20) 23.66(0.32) 23.64(0.23) 24.15(0.75) > 1G 23.58(0.23) 23.54(0.23) 23.62(0.24) 23.57(0.24) 23.64(0.27) 24.17(0.81) > 2G 24.00(0.65) 23.99(0.66) 24.01(0.67) 24.01(0.70) 24.13(0.80) 24.43(0.82) > 4G 24.04(0.66) 23.97(0.67) 24.05(0.71) 24.04(0.73) 24.15(0.82) 24.18(0.83) > 8G 23.97(0.66) 24.06(0.67) 23.98(0.68) 24.07(0.73) 24.13(0.81) 24.16(0.83) > 16G 24.05(0.66) 24.03(0.68) 24.02(0.68) 24.08(0.72) 24.18(0.82) 24.16(0.83) > > cyc-buf 128 256 512 1024 2048 4096 > splblk-size > 2M 24.05(0.65) 24.04(0.65) 24.58(0.65) 24.15(0.64) 24.14(0.64) 49.05(25.46) > 4M 23.98(0.65) 24.01(0.65) 24.29(0.65) 24.20(0.64) 24.18(0.66) 49.04(25.46) > 8M 24.02(0.65) 24.03(0.65) 24.25(0.65) 24.26(0.70) 24.15(0.64) 48.98(25.44) > 16M 24.01(0.65) 24.01(0.65) 24.30(0.65) 24.19(0.64) 24.12(0.65) 48.99(25.45) > 32M 23.97(0.65) 24.06(0.73) 24.23(0.65) 24.17(0.64) 24.19(0.64) 48.97(25.50) > 64M 24.06(0.66) 24.07(0.66) 24.27(0.66) 24.16(0.65) 24.17(0.65) 48.98(25.49) > 128M 24.03(0.67) 24.00(0.67) 24.27(0.66) 24.22(0.66) 24.19(0.66) 48.98(25.48) > 256M 24.12(0.67) 23.99(0.67) 24.27(0.67) 24.17(0.66) 24.12(0.66) 49.04(25.49) > 512M 24.06(0.70) 24.08(0.70) 24.26(0.70) 24.14(0.71) 24.19(0.70) 49.13(25.64) > 1G 24.20(0.82) 24.13(0.81) 24.36(0.81) 24.31(0.80) 24.33(0.81) 49.28(25.75) > 2G 24.19(0.81) 24.22(0.81) 24.37(0.81) 24.29(0.80) 24.28(0.82) 49.30(25.78) > 4G 25.29(1.90) 25.26(1.91) 25.49(1.91) 25.41(1.89) 25.50(1.90) 49.99(26.45) > 8G 25.33(1.90) 26.60(3.23) 26.87(3.21) 26.71(3.23) 26.64(3.22) 51.27(27.73) > 16G 25.28(1.90) 26.52(3.21) 29.47(5.86) 29.34(5.84) 29.38(5.86) 53.99(30.40) > > > >Thanks >Zhou Wenjian
